diff --git a/src-input/duk_api_bytecode.c b/src-input/duk_api_bytecode.c
index b56b176b..b2e0e7e3 100644
--- a/src-input/duk_api_bytecode.c
+++ b/src-input/duk_api_bytecode.c
@@ -74,9 +74,10 @@ DUK_LOCAL duk_uint8_t *duk__dump_hbuffer_raw(duk_hthread *thr, duk_uint8_t *p, d
 	DUK_ASSERT(len <= 0xffffffffUL);  /* buffer limits */
 	tmp32 = (duk_uint32_t) len;
 	DUK_RAW_WRITE_U32_BE(p, tmp32);
-	duk_memcpy((void *) p,
-	           (const void *) DUK_HBUFFER_GET_DATA_PTR(thr->heap, h),
-	           len);
+	/* When len == 0, buffer data pointer may be NULL. */
+	duk_memcpy_unsafe((void *) p,
+	                  (const void *) DUK_HBUFFER_GET_DATA_PTR(thr->heap, h),
+	                  len);
 	p += len;
 	return p;
 }
@@ -288,7 +289,7 @@ static duk_uint8_t *duk__dump_func(duk_hthread *thr, duk_hcompfunc *func, duk_bu
 	ins_end = DUK_HCOMPFUNC_GET_CODE_END(thr->heap, func);
 	DUK_ASSERT((duk_size_t) (ins_end - ins) == (duk_size_t) count_instr);
 #if defined(DUK_USE_INTEGER_BE)
-	duk_memcpy((void *) p, (const void *) ins, (size_t) (ins_end - ins));
+	duk_memcpy_unsafe((void *) p, (const void *) ins, (size_t) (ins_end - ins));
 	p += (size_t) (ins_end - ins);
 #else
 	while (ins != ins_end) {
diff --git a/src-input/duk_api_stack.c b/src-input/duk_api_stack.c
index 9f1f050d..d985a86f 100644
--- a/src-input/duk_api_stack.c
+++ b/src-input/duk_api_stack.c
@@ -1392,8 +1392,8 @@ DUK_EXTERNAL void duk_xcopymove_raw(duk_hthread *to_thr, duk_hthread *from_thr,
 		DUK_WO_NORETURN(return;);
 	}
 
-	/* copy values (no overlap even if to_thr == from_thr; that's not
-	 * allowed now anyway)
+	/* Copy values (no overlap even if to_thr == from_thr; that's not
+	 * allowed now anyway).
 	 */
 	DUK_ASSERT(nbytes > 0);
 	duk_memcpy((void *) to_thr->valstack_top, (const void *) src, (size_t) nbytes);
@@ -3417,7 +3417,8 @@ DUK_EXTERNAL void *duk_to_buffer_raw(duk_hthread *thr, duk_idx_t idx, duk_size_t
 	}
 
 	dst_data = (duk_uint8_t *) duk_push_buffer(thr, src_size, (mode == DUK_BUF_MODE_DYNAMIC) /*dynamic*/);
-	duk_memcpy((void *) dst_data, (const void *) src_data, (size_t) src_size);
+	/* dst_data may be NULL if size is zero. */
+	duk_memcpy_unsafe((void *) dst_data, (const void *) src_data, (size_t) src_size);
 
 	duk_replace(thr, idx);
  skip_copy:
@@ -5293,6 +5294,7 @@ DUK_INTERNAL void *duk_push_fixed_buffer_zero(duk_hthread *thr, duk_size_t len)
 	DUK_ASSERT_API_ENTRY(thr);
 
 	ptr = duk_push_buffer_raw(thr, len, 0);
+	DUK_ASSERT(ptr != NULL);
 #if !defined(DUK_USE_ZERO_BUFFER_DATA)
 	/* ES2015 requires zeroing even when DUK_USE_ZERO_BUFFER_DATA
 	 * is not set.
@@ -5952,7 +5954,7 @@ DUK_INTERNAL void duk_pack(duk_hthread *thr, duk_idx_t count) {
 	 * any refcount updates: net refcount changes are zero.
 	 */
 	tv_src = thr->valstack_top - count - 1;
-	duk_memcpy((void *) tv_dst, (const void *) tv_src, (size_t) count * sizeof(duk_tval));
+	duk_memcpy_unsafe((void *) tv_dst, (const void *) tv_src, (size_t) count * sizeof(duk_tval));
 
 	/* Overwrite result array to final value stack location and wipe
 	 * the rest; no refcount operations needed.
@@ -6614,7 +6616,7 @@ DUK_INTERNAL void duk_copy_tvals_incref(duk_hthread *thr, duk_tval *tv_dst, duk_
 	DUK_UNREF(thr);
 	DUK_ASSERT(count * sizeof(duk_tval) >= count);  /* no wrap */
 
-	duk_memcpy((void *) tv_dst, (const void *) tv_src, count * sizeof(duk_tval));
+	duk_memcpy_unsafe((void *) tv_dst, (const void *) tv_src, count * sizeof(duk_tval));
 
 	tv = tv_dst;
 	while (count-- > 0) {
diff --git a/src-input/duk_bi_buffer.c b/src-input/duk_bi_buffer.c
index 1f1d490a..1ffd99d3 100644
--- a/src-input/duk_bi_buffer.c
+++ b/src-input/duk_bi_buffer.c
@@ -443,6 +443,7 @@ DUK_INTERNAL void duk_hbufobj_push_uint8array_from_plain(duk_hthread *thr, duk_h
 DUK_INTERNAL void duk_hbufobj_push_validated_read(duk_hthread *thr, duk_hbufobj *h_bufobj, duk_uint8_t *p, duk_small_uint_t elem_size) {
 	duk_double_union du;
 
+	DUK_ASSERT(elem_size > 0);
 	duk_memcpy((void *) du.uc, (const void *) p, (size_t) elem_size);
 
 	switch (h_bufobj->elem_type) {
@@ -524,6 +525,7 @@ DUK_INTERNAL void duk_hbufobj_validated_write(duk_hthread *thr, duk_hbufobj *h_b
 		DUK_UNREACHABLE();
 	}
 
+	DUK_ASSERT(elem_size > 0);
 	duk_memcpy((void *) p, (const void *) du.uc, (size_t) elem_size);
 }
 
@@ -953,7 +955,7 @@ DUK_INTERNAL duk_ret_t duk_bi_typedarray_constructor(duk_hthread *thr) {
 		DUK_DDD(DUK_DDDPRINT("using memcpy: p_src=%p, p_dst=%p, byte_length=%ld",
 		                     (void *) p_src, (void *) p_dst, (long) byte_length));
 
-		duk_memcpy((void *) p_dst, (const void *) p_src, (size_t) byte_length);
+		duk_memcpy_unsafe((void *) p_dst, (const void *) p_src, (size_t) byte_length);
 		break;
 	}
 	case 1: {
@@ -1220,9 +1222,9 @@ DUK_INTERNAL duk_ret_t duk_bi_nodejs_buffer_tostring(duk_hthread *thr) {
 	 */
 
 	DUK_ASSERT(DUK_HBUFOBJ_VALID_BYTEOFFSET_EXCL(h_this, (duk_size_t) start_offset + slice_length));
-	duk_memcpy((void *) buf_slice,
-	           (const void *) (DUK_HBUFOBJ_GET_SLICE_BASE(thr->heap, h_this) + start_offset),
-	           (size_t) slice_length);
+	duk_memcpy_unsafe((void *) buf_slice,
+	                  (const void *) (DUK_HBUFOBJ_GET_SLICE_BASE(thr->heap, h_this) + start_offset),
+	                  (size_t) slice_length);
 
 	/* Use the equivalent of: new TextEncoder().encode(this) to convert the
 	 * string.  Result will be valid UTF-8; non-CESU-8 inputs are currently
@@ -1384,7 +1386,7 @@ DUK_INTERNAL duk_ret_t duk_bi_nodejs_buffer_fill(duk_hthread *thr) {
 		/* Handle single character fills as memset() even when
 		 * the fill data comes from a one-char argument.
 		 */
-		duk_memset((void *) p, (int) fill_str_ptr[0], (size_t) fill_length);
+		duk_memset_unsafe((void *) p, (int) fill_str_ptr[0], (size_t) fill_length);
 	} else if (fill_str_len > 1) {
 		duk_size_t i, n, t;
 
@@ -1435,9 +1437,9 @@ DUK_INTERNAL duk_ret_t duk_bi_nodejs_buffer_write(duk_hthread *thr) {
 
 	if (DUK_HBUFOBJ_VALID_SLICE(h_this)) {
 		/* Cannot overlap. */
-		duk_memcpy((void *) (DUK_HBUFOBJ_GET_SLICE_BASE(thr->heap, h_this) + offset),
-		           (const void *) str_data,
-		           (size_t) length);
+		duk_memcpy_unsafe((void *) (DUK_HBUFOBJ_GET_SLICE_BASE(thr->heap, h_this) + offset),
+		                  (const void *) str_data,
+		                  (size_t) length);
 	} else {
 		DUK_DDD(DUK_DDDPRINT("write() target buffer is not covered, silent ignore"));
 	}
@@ -1533,9 +1535,9 @@ DUK_INTERNAL duk_ret_t duk_bi_nodejs_buffer_copy(duk_hthread *thr) {
 		/* Must use memmove() because copy area may overlap (source and target
 		 * buffer may be the same, or from different slices.
 		 */
-		duk_memmove((void *) (DUK_HBUFOBJ_GET_SLICE_BASE(thr->heap, h_bufarg) + target_ustart),
-		            (const void *) (DUK_HBUFOBJ_GET_SLICE_BASE(thr->heap, h_this) + source_ustart),
-		            (size_t) copy_size);
+		duk_memmove_unsafe((void *) (DUK_HBUFOBJ_GET_SLICE_BASE(thr->heap, h_bufarg) + target_ustart),
+		                   (const void *) (DUK_HBUFOBJ_GET_SLICE_BASE(thr->heap, h_this) + source_ustart),
+		                   (size_t) copy_size);
 	} else {
 		DUK_DDD(DUK_DDDPRINT("buffer copy not covered by underlying buffer(s), ignoring"));
 	}
@@ -1721,7 +1723,7 @@ DUK_INTERNAL duk_ret_t duk_bi_typedarray_set(duk_hthread *thr) {
 			DUK_ASSERT(src_length == dst_length);
 
 			DUK_DDD(DUK_DDDPRINT("fast path: able to use memmove() because views are compatible"));
-			duk_memmove((void *) p_dst_base, (const void *) p_src_base, (size_t) dst_length);
+			duk_memmove_unsafe((void *) p_dst_base, (const void *) p_src_base, (size_t) dst_length);
 			return 0;
 		}
 		DUK_DDD(DUK_DDDPRINT("fast path: views are not compatible with a byte copy, copy by item"));
@@ -1764,7 +1766,7 @@ DUK_INTERNAL duk_ret_t duk_bi_typedarray_set(duk_hthread *thr) {
 			DUK_DDD(DUK_DDDPRINT("there is overlap, make a copy of the source"));
 			p_src_copy = (duk_uint8_t *) duk_push_fixed_buffer_nozero(thr, src_length);
 			DUK_ASSERT(p_src_copy != NULL);
-			duk_memcpy((void *) p_src_copy, (const void *) p_src_base, (size_t) src_length);
+			duk_memcpy_unsafe((void *) p_src_copy, (const void *) p_src_base, (size_t) src_length);
 
 			p_src_base = p_src_copy;  /* use p_src_base from now on */
 		}
@@ -1891,9 +1893,9 @@ DUK_LOCAL void duk__arraybuffer_plain_slice(duk_hthread *thr, duk_hbuffer *h_val
 	DUK_ASSERT(p_copy != NULL);
 	copy_length = slice_length;
 
-	duk_memcpy((void *) p_copy,
-	           (const void *) ((duk_uint8_t *) DUK_HBUFFER_GET_DATA_PTR(thr->heap, h_val) + start_offset),
-	           copy_length);
+	duk_memcpy_unsafe((void *) p_copy,
+	                  (const void *) ((duk_uint8_t *) DUK_HBUFFER_GET_DATA_PTR(thr->heap, h_val) + start_offset),
+	                  copy_length);
 }
 #endif /* DUK_USE_BUFFEROBJECT_SUPPORT */
 
@@ -2015,9 +2017,9 @@ DUK_INTERNAL duk_ret_t duk_bi_buffer_slice_shared(duk_hthread *thr) {
 		 * is left as zero.
 		 */
 		copy_length = DUK_HBUFOBJ_CLAMP_BYTELENGTH(h_this, slice_length);
-		duk_memcpy((void *) p_copy,
-		           (const void *) (DUK_HBUFOBJ_GET_SLICE_BASE(thr->heap, h_this) + start_offset),
-		           copy_length);
+		duk_memcpy_unsafe((void *) p_copy,
+		                  (const void *) (DUK_HBUFOBJ_GET_SLICE_BASE(thr->heap, h_this) + start_offset),
+		                  copy_length);
 
 		h_val = duk_known_hbuffer(thr, -1);
 
@@ -2209,9 +2211,9 @@ DUK_INTERNAL duk_ret_t duk_bi_nodejs_buffer_concat(duk_hthread *thr) {
 
 		if (h_bufobj->buf != NULL &&
 		    DUK_HBUFOBJ_VALID_SLICE(h_bufobj)) {
-			duk_memcpy((void *) p,
-			           (const void *) DUK_HBUFOBJ_GET_SLICE_BASE(thr->heap, h_bufobj),
-			           copy_size);
+			duk_memcpy_unsafe((void *) p,
+			                  (const void *) DUK_HBUFOBJ_GET_SLICE_BASE(thr->heap, h_bufobj),
+			                  copy_size);
 		} else {
 			/* Just skip, leaving zeroes in the result. */
 			;
diff --git a/src-input/duk_bi_string.c b/src-input/duk_bi_string.c
index 473357bf..b746da2d 100644
--- a/src-input/duk_bi_string.c
+++ b/src-input/duk_bi_string.c
@@ -1378,12 +1378,14 @@ DUK_INTERNAL duk_ret_t duk_bi_string_prototype_repeat(duk_hthread *thr) {
 
 	/* Temporary fixed buffer, later converted to string. */
 	buf = (duk_uint8_t *) duk_push_fixed_buffer_nozero(thr, result_len);
+	DUK_ASSERT(buf != NULL);
 	src = (const duk_uint8_t *) DUK_HSTRING_GET_DATA(h_input);
+	DUK_ASSERT(src != NULL);
 
 #if defined(DUK_USE_PREFER_SIZE)
 	p = buf;
 	while (count-- > 0) {
-		duk_memcpy((void *) p, (const void *) src, input_blen);  /* copy size may be zero */
+		duk_memcpy((void *) p, (const void *) src, input_blen);  /* copy size may be zero, but pointers are valid */
 		p += input_blen;
 	}
 #else  /* DUK_USE_PREFER_SIZE */
@@ -1400,7 +1402,7 @@ DUK_INTERNAL duk_ret_t duk_bi_string_prototype_repeat(duk_hthread *thr) {
 		                     (long) result_len));
 		if (remain <= copy_size) {
 			/* If result_len is zero, this case is taken and does
-			 * a zero size copy.
+			 * a zero size copy (with valid pointers).
 			 */
 			duk_memcpy((void *) p, (const void *) src, remain);
 			break;
diff --git a/src-input/duk_bi_symbol.c b/src-input/duk_bi_symbol.c
index 49c328d0..f9fcddb9 100644
--- a/src-input/duk_bi_symbol.c
+++ b/src-input/duk_bi_symbol.c
@@ -37,9 +37,10 @@ DUK_INTERNAL duk_ret_t duk_bi_symbol_constructor_shared(duk_hthread *thr) {
 	 *   +1    0xff after unique suffix for symbols with undefined description
 	 */
 	buf = (duk_uint8_t *) duk_push_fixed_buffer(thr, 1 + len + 1 + 17 + 1);
+	DUK_ASSERT(buf != NULL);
 	p = buf + 1;
 	DUK_ASSERT(desc != NULL || len == 0);  /* may be NULL if len is 0 */
-	duk_memcpy((void *) p, (const void *) desc, len);
+	duk_memcpy_unsafe((void *) p, (const void *) desc, len);
 	p += len;
 	if (magic == 0) {
 		/* Symbol(): create unique symbol.  Use two 32-bit values
diff --git a/src-input/duk_debug_fixedbuffer.c b/src-input/duk_debug_fixedbuffer.c
index 70ef15af..96b0dabf 100644
--- a/src-input/duk_debug_fixedbuffer.c
+++ b/src-input/duk_debug_fixedbuffer.c
@@ -18,7 +18,7 @@ DUK_INTERNAL void duk_fb_put_bytes(duk_fixedbuffer *fb, const duk_uint8_t *buffe
 	} else {
 		copylen = length;
 	}
-	duk_memcpy(fb->buffer + fb->offset, buffer, copylen);
+	duk_memcpy_unsafe(fb->buffer + fb->offset, buffer, copylen);
 	fb->offset += copylen;
 }
 
diff --git a/src-input/duk_debug_vsnprintf.c b/src-input/duk_debug_vsnprintf.c
index efbd767e..24001dbe 100644
--- a/src-input/duk_debug_vsnprintf.c
+++ b/src-input/duk_debug_vsnprintf.c
@@ -1019,6 +1019,7 @@ DUK_INTERNAL void duk_debug_format_funcptr(char *buf, duk_size_t buf_size, duk_u
 	duk_uint8_t *p = (duk_uint8_t *) buf;
 	duk_uint8_t *p_end = (duk_uint8_t *) (buf + buf_size - 1);
 
+	DUK_ASSERT(buf != NULL);
 	duk_memzero(buf, buf_size);
 
 	for (i = 0; i < fptr_size; i++) {
diff --git a/src-input/duk_debugger.c b/src-input/duk_debugger.c
index 6873142f..0125f3f3 100644
--- a/src-input/duk_debugger.c
+++ b/src-input/duk_debugger.c
@@ -309,6 +309,7 @@ DUK_INTERNAL void duk_debug_read_bytes(duk_hthread *thr, duk_uint8_t *data, duk_
 	DUK_ASSERT(thr != NULL);
 	heap = thr->heap;
 	DUK_ASSERT(heap != NULL);
+	DUK_ASSERT(data != NULL);
 
 	if (heap->dbg_read_cb == NULL) {
 		DUK_D(DUK_DPRINT("attempt to read %ld bytes in detached state, return zero data", (long) length));
diff --git a/src-input/duk_error.h b/src-input/duk_error.h
index 568301db..ea5d0133 100644
--- a/src-input/duk_error.h
+++ b/src-input/duk_error.h
@@ -423,7 +423,7 @@
 
 #if defined(DUK_USE_ASSERTIONS)
 #define DUK_ASSERT_SET_GARBAGE(ptr,size) do { \
-		duk_memset((void *) (ptr), 0x5a, size); \
+		duk_memset_unsafe((void *) (ptr), 0x5a, size); \
 	} while (0)
 #else
 #define DUK_ASSERT_SET_GARBAGE(ptr,size) do {} while (0)
diff --git a/src-input/duk_hbufobj.h b/src-input/duk_hbufobj.h
index ee66af67..b5c85240 100644
--- a/src-input/duk_hbufobj.h
+++ b/src-input/duk_hbufobj.h
@@ -47,7 +47,8 @@
 	} while (0)
 
 /* Get the current data pointer (caller must ensure buf != NULL) as a
- * duk_uint8_t ptr.
+ * duk_uint8_t ptr.  Note that the result may be NULL if the underlying
+ * buffer has zero size and is not a fixed buffer.
  */
 #define DUK_HBUFOBJ_GET_SLICE_BASE(heap,h) \
 	(DUK_ASSERT_EXPR((h) != NULL), DUK_ASSERT_EXPR((h)->buf != NULL), \
diff --git a/src-input/duk_heap_memory.c b/src-input/duk_heap_memory.c
index 5a537b5a..efb7b393 100644
--- a/src-input/duk_heap_memory.c
+++ b/src-input/duk_heap_memory.c
@@ -127,7 +127,6 @@ DUK_INTERNAL void *duk_heap_mem_alloc_zeroed(duk_heap *heap, duk_size_t size) {
 
 	res = DUK_ALLOC(heap, size);
 	if (DUK_LIKELY(res != NULL)) {
-		/* assume memset with zero size is OK */
 		duk_memzero(res, size);
 	}
 	return res;
diff --git a/src-input/duk_heap_stringtable.c b/src-input/duk_heap_stringtable.c
index ee785f68..fba53307 100644
--- a/src-input/duk_heap_stringtable.c
+++ b/src-input/duk_heap_stringtable.c
@@ -690,7 +690,7 @@ DUK_LOCAL duk_hstring *duk__strtab_romstring_lookup(duk_heap *heap, const duk_ui
 	while (curr != NULL) {
 		if (strhash == DUK_HSTRING_GET_HASH(curr) &&
 		    blen == DUK_HSTRING_GET_BYTELEN(curr) &&
-		    duk_memcmp((const void *) str, (const void *) DUK_HSTRING_GET_DATA(curr), blen) == 0) {
+		    duk_memcmp_unsafe((const void *) str, (const void *) DUK_HSTRING_GET_DATA(curr), blen) == 0) {
 			DUK_DDD(DUK_DDDPRINT("intern check: rom string: %!O, computed hash 0x%08lx, rom hash 0x%08lx",
 			                     curr, (unsigned long) strhash, (unsigned long) DUK_HSTRING_GET_HASH(curr)));
 			return curr;
@@ -710,6 +710,7 @@ DUK_INTERNAL duk_hstring *duk_heap_strtable_intern(duk_heap *heap, const duk_uin
 
 	/* Preliminaries. */
 
+	/* XXX: maybe just require 'str != NULL' even for zero size? */
 	DUK_ASSERT(heap != NULL);
 	DUK_ASSERT(blen == 0 || str != NULL);
 	DUK_ASSERT(blen <= DUK_HSTRING_MAX_BYTELEN);  /* Caller is responsible for ensuring this. */
@@ -728,7 +729,7 @@ DUK_INTERNAL duk_hstring *duk_heap_strtable_intern(duk_heap *heap, const duk_uin
 	while (h != NULL) {
 		if (DUK_HSTRING_GET_HASH(h) == strhash &&
 		    DUK_HSTRING_GET_BYTELEN(h) == blen &&
-		    duk_memcmp((const void *) str, (const void *) DUK_HSTRING_GET_DATA(h), (size_t) blen) == 0) {
+		    duk_memcmp_unsafe((const void *) str, (const void *) DUK_HSTRING_GET_DATA(h), (size_t) blen) == 0) {
 			/* Found existing entry. */
 			DUK_STATS_INC(heap, stats_strtab_intern_hit);
 			return h;
diff --git a/src-input/duk_hobject_props.c b/src-input/duk_hobject_props.c
index fa274480..2883623a 100644
--- a/src-input/duk_hobject_props.c
+++ b/src-input/duk_hobject_props.c
@@ -811,9 +811,9 @@ DUK_INTERNAL void duk_hobject_realloc_props(duk_hthread *thr,
 	DUK_ASSERT(new_a != NULL || array_copy_size == 0U);
 	DUK_ASSERT(DUK_HOBJECT_GET_PROPS(thr->heap, obj) != NULL || array_copy_size == 0U);
 	DUK_ASSERT(DUK_HOBJECT_GET_ASIZE(obj) > 0 || array_copy_size == 0U);
-	duk_memcpy((void *) new_a,
-	           (const void *) DUK_HOBJECT_A_GET_BASE(thr->heap, obj),
-	           array_copy_size);
+	duk_memcpy_unsafe((void *) new_a,
+	                  (const void *) DUK_HOBJECT_A_GET_BASE(thr->heap, obj),
+	                  array_copy_size);
 
 	for (i = DUK_HOBJECT_GET_ASIZE(obj); i < new_a_size; i++) {
 		duk_tval *tv = &new_a[i];
diff --git a/src-input/duk_js_ops.c b/src-input/duk_js_ops.c
index 0f76768f..833b394e 100644
--- a/src-input/duk_js_ops.c
+++ b/src-input/duk_js_ops.c
@@ -727,11 +727,11 @@ DUK_INTERNAL duk_small_int_t duk_js_data_compare(const duk_uint8_t *buf1, const
 	prefix_len = (len1 <= len2 ? len1 : len2);
 
 	/* duk_memcmp() is guaranteed to return zero (equal) for zero length
-	 * inputs so no zero length check is needed.
+	 * inputs.
 	 */
-	rc = duk_memcmp((const void *) buf1,
-	                (const void *) buf2,
-	                (size_t) prefix_len);
+	rc = duk_memcmp_unsafe((const void *) buf1,
+	                       (const void *) buf2,
+	                       (size_t) prefix_len);
 
 	if (rc < 0) {
 		return -1;
diff --git a/src-input/duk_numconv.c b/src-input/duk_numconv.c
index 9d631f3c..214872b1 100644
--- a/src-input/duk_numconv.c
+++ b/src-input/duk_numconv.c
@@ -674,6 +674,7 @@ DUK_LOCAL duk_size_t duk__dragon4_format_uint32(duk_uint8_t *buf, duk_uint32_t x
 	duk_small_int_t dig;
 	duk_uint32_t t;
 
+	DUK_ASSERT(buf != NULL);
 	DUK_ASSERT(radix >= 2 && radix <= 36);
 
 	/* A 32-bit unsigned integer formats to at most 32 digits (the
diff --git a/src-input/duk_util.h b/src-input/duk_util.h
index d76c5d9c..ad83cac0 100644
--- a/src-input/duk_util.h
+++ b/src-input/duk_util.h
@@ -315,12 +315,13 @@ struct duk_bufwriter_ctx {
 		(bw_ctx)->p += duk__enc_len; \
 	} while (0)
 /* XXX: add temporary duk__p pointer here too; sharing */
+/* XXX: avoid unsafe variants */
 #define DUK_BW_WRITE_RAW_BYTES(thr,bw_ctx,valptr,valsz) do { \
 		const void *duk__valptr; \
 		duk_size_t duk__valsz; \
 		duk__valptr = (const void *) (valptr); \
 		duk__valsz = (duk_size_t) (valsz); \
-		duk_memcpy((void *) ((bw_ctx)->p), duk__valptr, duk__valsz); \
+		duk_memcpy_unsafe((void *) ((bw_ctx)->p), duk__valptr, duk__valsz); \
 		(bw_ctx)->p += duk__valsz; \
 	} while (0)
 #define DUK_BW_WRITE_RAW_CSTRING(thr,bw_ctx,val) do { \
@@ -328,31 +329,31 @@ struct duk_bufwriter_ctx {
 		duk_size_t duk__val_len; \
 		duk__val = (const duk_uint8_t *) (val); \
 		duk__val_len = DUK_STRLEN((const char *) duk__val); \
-		duk_memcpy((void *) ((bw_ctx)->p), (const void *) duk__val, duk__val_len); \
+		duk_memcpy_unsafe((void *) ((bw_ctx)->p), (const void *) duk__val, duk__val_len); \
 		(bw_ctx)->p += duk__val_len; \
 	} while (0)
 #define DUK_BW_WRITE_RAW_HSTRING(thr,bw_ctx,val) do { \
 		duk_size_t duk__val_len; \
 		duk__val_len = DUK_HSTRING_GET_BYTELEN((val)); \
-		duk_memcpy((void *) ((bw_ctx)->p), (const void *) DUK_HSTRING_GET_DATA((val)), duk__val_len); \
+		duk_memcpy_unsafe((void *) ((bw_ctx)->p), (const void *) DUK_HSTRING_GET_DATA((val)), duk__val_len); \
 		(bw_ctx)->p += duk__val_len; \
 	} while (0)
 #define DUK_BW_WRITE_RAW_HBUFFER(thr,bw_ctx,val) do { \
 		duk_size_t duk__val_len; \
 		duk__val_len = DUK_HBUFFER_GET_SIZE((val)); \
-		duk_memcpy((void *) ((bw_ctx)->p), (const void *) DUK_HBUFFER_GET_DATA_PTR((thr)->heap, (val)), duk__val_len); \
+		duk_memcpy_unsafe((void *) ((bw_ctx)->p), (const void *) DUK_HBUFFER_GET_DATA_PTR((thr)->heap, (val)), duk__val_len); \
 		(bw_ctx)->p += duk__val_len; \
 	} while (0)
 #define DUK_BW_WRITE_RAW_HBUFFER_FIXED(thr,bw_ctx,val) do { \
 		duk_size_t duk__val_len; \
 		duk__val_len = DUK_HBUFFER_FIXED_GET_SIZE((val)); \
-		duk_memcpy((void *) ((bw_ctx)->p), (const void *) DUK_HBUFFER_FIXED_GET_DATA_PTR((thr)->heap, (val)), duk__val_len); \
+		duk_memcpy_unsafe((void *) ((bw_ctx)->p), (const void *) DUK_HBUFFER_FIXED_GET_DATA_PTR((thr)->heap, (val)), duk__val_len); \
 		(bw_ctx)->p += duk__val_len; \
 	} while (0)
 #define DUK_BW_WRITE_RAW_HBUFFER_DYNAMIC(thr,bw_ctx,val) do { \
 		duk_size_t duk__val_len; \
 		duk__val_len = DUK_HBUFFER_DYNAMIC_GET_SIZE((val)); \
-		duk_memcpy((void *) ((bw_ctx)->p), (const void *) DUK_HBUFFER_DYNAMIC_GET_DATA_PTR((thr)->heap, (val)), duk__val_len); \
+		duk_memcpy_unsafe((void *) ((bw_ctx)->p), (const void *) DUK_HBUFFER_DYNAMIC_GET_DATA_PTR((thr)->heap, (val)), duk__val_len); \
 		(bw_ctx)->p += duk__val_len; \
 	} while (0)
 
@@ -416,13 +417,14 @@ struct duk_bufwriter_ctx {
 		DUK_BW_WRITE_RAW_CESU8((thr), (bw_ctx), (cp)); \
 	} while (0)
 /* XXX: add temporary duk__p pointer here too; sharing */
+/* XXX: avoid unsafe */
 #define DUK_BW_WRITE_ENSURE_BYTES(thr,bw_ctx,valptr,valsz) do { \
 		const void *duk__valptr; \
 		duk_size_t duk__valsz; \
 		duk__valptr = (const void *) (valptr); \
 		duk__valsz = (duk_size_t) (valsz); \
 		DUK_BW_ENSURE((thr), (bw_ctx), duk__valsz); \
-		duk_memcpy((void *) ((bw_ctx)->p), duk__valptr, duk__valsz); \
+		duk_memcpy_unsafe((void *) ((bw_ctx)->p), duk__valptr, duk__valsz); \
 		(bw_ctx)->p += duk__valsz; \
 	} while (0)
 #define DUK_BW_WRITE_ENSURE_CSTRING(thr,bw_ctx,val) do { \
@@ -431,35 +433,35 @@ struct duk_bufwriter_ctx {
 		duk__val = (const duk_uint8_t *) (val); \
 		duk__val_len = DUK_STRLEN((const char *) duk__val); \
 		DUK_BW_ENSURE((thr), (bw_ctx), duk__val_len); \
-		duk_memcpy((void *) ((bw_ctx)->p), (const void *) duk__val, duk__val_len); \
+		duk_memcpy_unsafe((void *) ((bw_ctx)->p), (const void *) duk__val, duk__val_len); \
 		(bw_ctx)->p += duk__val_len; \
 	} while (0)
 #define DUK_BW_WRITE_ENSURE_HSTRING(thr,bw_ctx,val) do { \
 		duk_size_t duk__val_len; \
 		duk__val_len = DUK_HSTRING_GET_BYTELEN((val)); \
 		DUK_BW_ENSURE((thr), (bw_ctx), duk__val_len); \
-		duk_memcpy((void *) ((bw_ctx)->p), (const void *) DUK_HSTRING_GET_DATA((val)), duk__val_len); \
+		duk_memcpy_unsafe((void *) ((bw_ctx)->p), (const void *) DUK_HSTRING_GET_DATA((val)), duk__val_len); \
 		(bw_ctx)->p += duk__val_len; \
 	} while (0)
 #define DUK_BW_WRITE_ENSURE_HBUFFER(thr,bw_ctx,val) do { \
 		duk_size_t duk__val_len; \
 		duk__val_len = DUK_HBUFFER_GET_SIZE((val)); \
 		DUK_BW_ENSURE((thr), (bw_ctx), duk__val_len); \
-		duk_memcpy((void *) ((bw_ctx)->p), (const void *) DUK_HBUFFER_GET_DATA_PTR((thr)->heap, (val)), duk__val_len); \
+		duk_memcpy_unsafe((void *) ((bw_ctx)->p), (const void *) DUK_HBUFFER_GET_DATA_PTR((thr)->heap, (val)), duk__val_len); \
 		(bw_ctx)->p += duk__val_len; \
 	} while (0)
 #define DUK_BW_WRITE_ENSURE_HBUFFER_FIXED(thr,bw_ctx,val) do { \
 		duk_size_t duk__val_len; \
 		duk__val_len = DUK_HBUFFER_FIXED_GET_SIZE((val)); \
 		DUK_BW_ENSURE((thr), (bw_ctx), duk__val_len); \
-		duk_memcpy((void *) ((bw_ctx)->p), (const void *) DUK_HBUFFER_FIXED_GET_DATA_PTR((thr)->heap, (val)), duk__val_len); \
+		duk_memcpy_unsafe((void *) ((bw_ctx)->p), (const void *) DUK_HBUFFER_FIXED_GET_DATA_PTR((thr)->heap, (val)), duk__val_len); \
 		(bw_ctx)->p += duk__val_len; \
 	} while (0)
 #define DUK_BW_WRITE_ENSURE_HBUFFER_DYNAMIC(thr,bw_ctx,val) do { \
 		duk_size_t duk__val_len; \
 		duk__val_len = DUK_HBUFFER_DYNAMIC_GET_SIZE((val)); \
 		DUK_BW_ENSURE((thr), (bw_ctx), duk__val_len); \
-		duk_memcpy((void *) ((bw_ctx)->p), (const void *) DUK_HBUFFER_DYNAMIC_GET_DATA_PTR((thr)->heap, (val)), duk__val_len); \
+		duk_memcpy_unsafe((void *) ((bw_ctx)->p), (const void *) DUK_HBUFFER_DYNAMIC_GET_DATA_PTR((thr)->heap, (val)), duk__val_len); \
 		(bw_ctx)->p += duk__val_len; \
 	} while (0)
 
@@ -542,11 +544,126 @@ DUK_INTERNAL_DECL void duk_raw_write_double_be(duk_uint8_t **p, duk_double_t val
 DUK_INTERNAL_DECL void duk_byteswap_bytes(duk_uint8_t *p, duk_small_uint_t len);
 #endif
 
-DUK_INTERNAL_DECL void duk_memcpy(void *dst, const void *src, duk_size_t len);
-DUK_INTERNAL_DECL void duk_memmove(void *dst, const void *src, duk_size_t len);
+/* memcpy(), memmove() etc wrappers.  The plain variants like duk_memcpy()
+ * assume C99+ and 'src' and 'dst' pointers must be non-NULL even when the
+ * operation size is zero.  The unsafe variants like duk_memcpy_safe() deal
+ * with the zero size case explicitly, and allow NULL pointers in that case
+ * (which is undefined behavior in C99+).  For the majority of actual targets
+ * a NULL pointer with a zero length is fine in practice.  These wrappers are
+ * macros to force inlining; because there are hundreds of call sites, even a
+ * few extra bytes per call site adds up to ~1kB footprint.
+ */
+#if defined(DUK_USE_ALLOW_UNDEFINED_BEHAVIOR)
+#define duk_memcpy(dst,src,len)  do { \
+		void *duk__dst = (dst); \
+		const void *duk__src = (src); \
+		duk_size_t duk__len = (len); \
+		DUK_ASSERT(duk__dst != NULL || duk__len == 0U); \
+		DUK_ASSERT(duk__src != NULL || duk__len == 0U); \
+		(void) DUK_MEMCPY(duk__dst, duk__src, (size_t) duk__len); \
+	} while (0)
+#define duk_memcpy_unsafe(dst,src,len)  duk_memcpy((dst), (src), (len))
+#define duk_memmove(dst,src,len)  do { \
+		void *duk__dst = (dst); \
+		const void *duk__src = (src); \
+		duk_size_t duk__len = (len); \
+		DUK_ASSERT(duk__dst != NULL || duk__len == 0U); \
+		DUK_ASSERT(duk__src != NULL || duk__len == 0U); \
+		(void) DUK_MEMMOVE(duk__dst, duk__src, (size_t) duk__len); \
+	} while (0)
+#define duk_memmove_unsafe(dst,src,len)  duk_memmove((dst), (src), (len))
+#define duk_memset(dst,val,len)  do { \
+		void *duk__dst = (dst); \
+		duk_small_int_t duk__val = (val); \
+		duk_size_t duk__len = (len); \
+		DUK_ASSERT(duk__dst != NULL || duk__len == 0U); \
+		(void) DUK_MEMSET(duk__dst, duk__val, (size_t) duk__len); \
+	} while (0)
+#define duk_memset_unsafe(dst,val,len)  duk_memset((dst), (val), (len))
+#define duk_memzero(dst,len)  do { \
+		void *duk__dst = (dst); \
+		duk_size_t duk__len = (len); \
+		DUK_ASSERT(duk__dst != NULL || duk__len == 0U); \
+		(void) DUK_MEMZERO(duk__dst, (size_t) duk__len); \
+	} while (0)
+#define duk_memzero_unsafe(dst,len)  duk_memzero((dst), (len))
+#else  /* DUK_USE_ALLOW_UNDEFINED_BEHAVIOR */
+#define duk_memcpy(dst,src,len)  do { \
+		void *duk__dst = (dst); \
+		const void *duk__src = (src); \
+		duk_size_t duk__len = (len); \
+		DUK_ASSERT(duk__dst != NULL); \
+		DUK_ASSERT(duk__src != NULL); \
+		(void) DUK_MEMCPY(duk__dst, duk__src, (size_t) duk__len); \
+	} while (0)
+#define duk_memcpy_unsafe(dst,src,len)  do { \
+		void *duk__dst = (dst); \
+		const void *duk__src = (src); \
+		duk_size_t duk__len = (len); \
+		DUK_ASSERT(duk__dst != NULL || duk__len == 0U); \
+		DUK_ASSERT(duk__src != NULL || duk__len == 0U); \
+		if (DUK_LIKELY(duk__len > 0U)) { \
+			DUK_ASSERT(duk__dst != NULL); \
+			DUK_ASSERT(duk__src != NULL); \
+			(void) DUK_MEMCPY(duk__dst, duk__src, (size_t) duk__len); \
+		} \
+	} while (0)
+#define duk_memmove(dst,src,len)  do { \
+		void *duk__dst = (dst); \
+		const void *duk__src = (src); \
+		duk_size_t duk__len = (len); \
+		DUK_ASSERT(duk__dst != NULL); \
+		DUK_ASSERT(duk__src != NULL); \
+		(void) DUK_MEMMOVE(duk__dst, duk__src, (size_t) duk__len); \
+	} while (0)
+#define duk_memmove_unsafe(dst,src,len)  do { \
+		void *duk__dst = (dst); \
+		const void *duk__src = (src); \
+		duk_size_t duk__len = (len); \
+		DUK_ASSERT(duk__dst != NULL || duk__len == 0U); \
+		DUK_ASSERT(duk__src != NULL || duk__len == 0U); \
+		if (DUK_LIKELY(duk__len > 0U)) { \
+			DUK_ASSERT(duk__dst != NULL); \
+			DUK_ASSERT(duk__src != NULL); \
+			(void) DUK_MEMMOVE(duk__dst, duk__src, (size_t) duk__len); \
+		} \
+	} while (0)
+#define duk_memset(dst,val,len)  do { \
+		void *duk__dst = (dst); \
+		duk_small_int_t duk__val = (val); \
+		duk_size_t duk__len = (len); \
+		DUK_ASSERT(duk__dst != NULL); \
+		(void) DUK_MEMSET(duk__dst, duk__val, (size_t) duk__len); \
+	} while (0)
+#define duk_memset_unsafe(dst,val,len)  do { \
+		void *duk__dst = (dst); \
+		duk_small_int_t duk__val = (val); \
+		duk_size_t duk__len = (len); \
+		DUK_ASSERT(duk__dst != NULL || duk__len == 0U); \
+		if (DUK_LIKELY(duk__len > 0U)) { \
+			DUK_ASSERT(duk__dst != NULL); \
+			(void) DUK_MEMSET(duk__dst, duk__val, (size_t) duk__len); \
+		} \
+	} while (0)
+#define duk_memzero(dst,len)  do { \
+		void *duk__dst = (dst); \
+		duk_size_t duk__len = (len); \
+		DUK_ASSERT(duk__dst != NULL); \
+		(void) DUK_MEMZERO(duk__dst, (size_t) duk__len); \
+	} while (0)
+#define duk_memzero_unsafe(dst,len)  do { \
+		void *duk__dst = (dst); \
+		duk_size_t duk__len = (len); \
+		DUK_ASSERT(duk__dst != NULL || duk__len == 0U); \
+		if (DUK_LIKELY(duk__len > 0U)) { \
+			DUK_ASSERT(duk__dst != NULL); \
+			(void) DUK_MEMZERO(duk__dst, (size_t) duk__len); \
+		} \
+	} while (0)
+#endif  /* DUK_USE_ALLOW_UNDEFINED_BEHAVIOR */
+
 DUK_INTERNAL_DECL duk_small_int_t duk_memcmp(const void *s1, const void *s2, duk_size_t len);
-DUK_INTERNAL_DECL void duk_memset(void *s, duk_small_int_t c, duk_size_t len);
-DUK_INTERNAL_DECL void duk_memzero(void *s, duk_size_t len);
+DUK_INTERNAL_DECL duk_small_int_t duk_memcmp_unsafe(const void *s1, const void *s2, duk_size_t len);
 
 DUK_INTERNAL_DECL duk_bool_t duk_is_whole_get_int32_nonegzero(duk_double_t x, duk_int32_t *ival);
 DUK_INTERNAL_DECL duk_bool_t duk_is_whole_get_int32(duk_double_t x, duk_int32_t *ival);
diff --git a/src-input/duk_util_bufwriter.c b/src-input/duk_util_bufwriter.c
index d7767009..b82b7eb1 100644
--- a/src-input/duk_util_bufwriter.c
+++ b/src-input/duk_util_bufwriter.c
@@ -4,6 +4,10 @@
 
 #include "duk_internal.h"
 
+/* XXX: Avoid duk_{memcmp,memmove}_unsafe() by imposing a minimum length of
+ * >0 for the underlying dynamic buffer.
+ */
+
 /*
  *  Macro support functions (use only macros in calling code)
  */
@@ -15,6 +19,9 @@ DUK_LOCAL void duk__bw_update_ptrs(duk_hthread *thr, duk_bufwriter_ctx *bw_ctx,
 	DUK_ASSERT(bw_ctx != NULL);
 	DUK_UNREF(thr);
 
+	/* 'p' might be NULL when the underlying buffer is zero size.  If so,
+	 * the resulting pointers are not used unsafely.
+	 */
 	p = (duk_uint8_t *) DUK_HBUFFER_DYNAMIC_GET_DATA_PTR(thr->heap, bw_ctx->buf);
 	DUK_ASSERT(p != NULL || (DUK_HBUFFER_DYNAMIC_GET_SIZE(bw_ctx->buf) == 0 && curr_offset == 0 && new_length == 0));
 	bw_ctx->p = p + curr_offset;
@@ -23,7 +30,6 @@ DUK_LOCAL void duk__bw_update_ptrs(duk_hthread *thr, duk_bufwriter_ctx *bw_ctx,
 }
 
 DUK_INTERNAL void duk_bw_init(duk_hthread *thr, duk_bufwriter_ctx *bw_ctx, duk_hbuffer_dynamic *h_buf) {
-
 	DUK_ASSERT(thr != NULL);
 	DUK_ASSERT(bw_ctx != NULL);
 	DUK_ASSERT(h_buf != NULL);
@@ -38,6 +44,7 @@ DUK_INTERNAL void duk_bw_init_pushbuf(duk_hthread *thr, duk_bufwriter_ctx *bw_ct
 
 	(void) duk_push_dynamic_buffer(thr, buf_size);
 	bw_ctx->buf = (duk_hbuffer_dynamic *) duk_known_hbuffer(thr, -1);
+	DUK_ASSERT(bw_ctx->buf != NULL);
 	duk__bw_update_ptrs(thr, bw_ctx, 0, buf_size);
 }
 
@@ -105,9 +112,9 @@ DUK_INTERNAL void duk_bw_write_raw_slice(duk_hthread *thr, duk_bufwriter_ctx *bw
 	DUK_UNREF(thr);
 
 	p_base = bw->p_base;
-	duk_memcpy((void *) bw->p,
-	           (const void *) (p_base + src_off),
-	           (size_t) len);
+	duk_memcpy_unsafe((void *) bw->p,
+	                  (const void *) (p_base + src_off),
+	                  (size_t) len);
 	bw->p += len;
 }
 
@@ -137,12 +144,12 @@ DUK_INTERNAL void duk_bw_insert_raw_bytes(duk_hthread *thr, duk_bufwriter_ctx *b
 	move_sz = buf_sz - dst_off;
 
 	DUK_ASSERT(p_base != NULL);  /* buffer size is >= 1 */
-	duk_memmove((void *) (p_base + dst_off + len),
-	            (const void *) (p_base + dst_off),
-	            (size_t) move_sz);
-	duk_memcpy((void *) (p_base + dst_off),
-	           (const void *) buf,
-	           (size_t) len);
+	duk_memmove_unsafe((void *) (p_base + dst_off + len),
+	                   (const void *) (p_base + dst_off),
+	                   (size_t) move_sz);
+	duk_memcpy_unsafe((void *) (p_base + dst_off),
+	                  (const void *) buf,
+	                  (size_t) len);
 	bw->p += len;
 }
 
@@ -184,12 +191,12 @@ DUK_INTERNAL void duk_bw_insert_raw_slice(duk_hthread *thr, duk_bufwriter_ctx *b
 	move_sz = buf_sz - dst_off;
 
 	DUK_ASSERT(p_base != NULL);  /* buffer size is >= 1 */
-	duk_memmove((void *) (p_base + dst_off + len),
-	            (const void *) (p_base + dst_off),
-	            (size_t) move_sz);
-	duk_memcpy((void *) (p_base + dst_off),
-	           (const void *) (p_base + src_off),
-	           (size_t) len);
+	duk_memmove_unsafe((void *) (p_base + dst_off + len),
+	                   (const void *) (p_base + dst_off),
+	                   (size_t) move_sz);
+	duk_memcpy_unsafe((void *) (p_base + dst_off),
+	                  (const void *) (p_base + src_off),
+	                  (size_t) len);
 	bw->p += len;
 }
 
@@ -222,7 +229,7 @@ DUK_INTERNAL duk_uint8_t *duk_bw_insert_raw_area(duk_hthread *thr, duk_bufwriter
 	move_sz = buf_sz - off;
 	p_dst = p_base + off + len;
 	p_src = p_base + off;
-	duk_memmove((void *) p_dst, (const void *) p_src, (size_t) move_sz);
+	duk_memmove_unsafe((void *) p_dst, (const void *) p_src, (size_t) move_sz);
 	return p_src;  /* point to start of 'reserved area' */
 }
 
@@ -253,9 +260,9 @@ DUK_INTERNAL void duk_bw_remove_raw_slice(duk_hthread *thr, duk_bufwriter_ctx *b
 	p_dst = p_base + off;
 	p_src = p_dst + len;
 	move_sz = (duk_size_t) (bw->p - p_src);
-	duk_memmove((void *) p_dst,
-	            (const void *) p_src,
-	            (size_t) move_sz);
+	duk_memmove_unsafe((void *) p_dst,
+	                   (const void *) p_src,
+	                   (size_t) move_sz);
 	bw->p -= len;
 }
 
diff --git a/src-input/duk_util_memory.c b/src-input/duk_util_memory.c
index b4c74214..eb3c7042 100644
--- a/src-input/duk_util_memory.c
+++ b/src-input/duk_util_memory.c
@@ -1,67 +1,36 @@
 /*
- *  Memcpy() etc.
+ *  Memory utils.
  */
 
 #include "duk_internal.h"
 
-DUK_INTERNAL void duk_memcpy(void *dst, const void *src, duk_size_t len) {
-#if !defined(DUK_USE_ALLOW_UNDEFINED_BEHAVIOR)
-	/* For portability reasons both 'src' and 'dst' must be valid and
-	 * non-NULL even if len is zero.  Check for that explicitly to avoid
-	 * depending on platform specific behavior.  For the vast majority of
-	 * actual targets a NULL pointer with a zero length is fine.
-	 */
-	if (DUK_UNLIKELY(len == 0U)) {
-		return;
-	}
-	DUK_ASSERT(src != NULL);
-	DUK_ASSERT(dst != NULL);
-#else
-	DUK_ASSERT(src != NULL || len == 0U);
-	DUK_ASSERT(dst != NULL || len == 0U);
-#endif
-
-	(void) DUK_MEMCPY(dst, src, (size_t) len);
+#if defined(DUK_USE_ALLOW_UNDEFINED_BEHAVIOR)
+DUK_INTERNAL DUK_INLINE duk_small_int_t duk_memcmp_unsafe(const void *s1, const void *s2, duk_size_t len) {
+	DUK_ASSERT(s1 != NULL || len == 0U);
+	DUK_ASSERT(s2 != NULL || len == 0U);
+	return DUK_MEMCMP(s1, s2, (size_t) len);
 }
 
-DUK_INTERNAL void duk_memmove(void *dst, const void *src, duk_size_t len) {
-#if !defined(DUK_USE_ALLOW_UNDEFINED_BEHAVIOR)
-	if (DUK_UNLIKELY(len == 0U)) {
-		return;
-	}
-	DUK_ASSERT(src != NULL);
-	DUK_ASSERT(dst != NULL);
-#else
-	DUK_ASSERT(src != NULL || len == 0U);
-	DUK_ASSERT(dst != NULL || len == 0U);
-#endif
-
-	(void) DUK_MEMMOVE(dst, src, (size_t) len);
+DUK_INTERNAL DUK_INLINE duk_small_int_t duk_memcmp(const void *s1, const void *s2, duk_size_t len) {
+	DUK_ASSERT(s1 != NULL);
+	DUK_ASSERT(s2 != NULL);
+	return DUK_MEMCMP(s1, s2, (size_t) len);
 }
-
-DUK_INTERNAL duk_small_int_t duk_memcmp(const void *s1, const void *s2, duk_size_t len) {
-	duk_small_int_t ret;
-
-#if !defined(DUK_USE_ALLOW_UNDEFINED_BEHAVIOR)
+#else  /* DUK_USE_ALLOW_UNDEFINED_BEHAVIOR */
+DUK_INTERNAL DUK_INLINE duk_small_int_t duk_memcmp_unsafe(const void *s1, const void *s2, duk_size_t len) {
+	DUK_ASSERT(s1 != NULL || len == 0U);
+	DUK_ASSERT(s2 != NULL || len == 0U);
 	if (DUK_UNLIKELY(len == 0U)) {
 		return 0;
 	}
 	DUK_ASSERT(s1 != NULL);
 	DUK_ASSERT(s2 != NULL);
-#else
-	DUK_ASSERT(s1 != NULL || len == 0U);
-	DUK_ASSERT(s2 != NULL || len == 0U);
-#endif
-
-	ret = (duk_small_int_t) DUK_MEMCMP(s1, s2, (size_t) len);
-	DUK_ASSERT(ret == 0 || len > 0);  /* If len == 0, must compare equal. */
-	return ret;
-}
-
-DUK_INTERNAL void duk_memset(void *s, duk_small_int_t c, duk_size_t len) {
-	(void) DUK_MEMSET(s, (int) c, (size_t) len);
+	return duk_memcmp(s1, s2, len);
 }
 
-DUK_INTERNAL void duk_memzero(void *s, duk_size_t len) {
-	(void) DUK_MEMZERO(s, (size_t) len);
+DUK_INTERNAL DUK_INLINE duk_small_int_t duk_memcmp(const void *s1, const void *s2, duk_size_t len) {
+	DUK_ASSERT(s1 != NULL);
+	DUK_ASSERT(s2 != NULL);
+	return DUK_MEMCMP(s1, s2, (size_t) len);
 }
+#endif  /* DUK_USE_ALLOW_UNDEFINED_BEHAVIOR */