diff --git a/py/gc.c b/py/gc.c
index 41bbaa1b57..be35dc2ccc 100644
--- a/py/gc.c
+++ b/py/gc.c
@@ -118,9 +118,9 @@ void gc_init(void *start, void *end) {
     // => T = A * (1 + BLOCKS_PER_ATB / BLOCKS_PER_FTB + BLOCKS_PER_ATB * BYTES_PER_BLOCK)
     size_t total_byte_len = (byte *)end - (byte *)start;
     #if MICROPY_ENABLE_FINALISER
-    MP_STATE_MEM(gc_alloc_table_byte_len) = total_byte_len * BITS_PER_BYTE / (BITS_PER_BYTE + BITS_PER_BYTE * BLOCKS_PER_ATB / BLOCKS_PER_FTB + BITS_PER_BYTE * BLOCKS_PER_ATB * BYTES_PER_BLOCK);
+    MP_STATE_MEM(gc_alloc_table_byte_len) = total_byte_len * MP_BITS_PER_BYTE / (MP_BITS_PER_BYTE + MP_BITS_PER_BYTE * BLOCKS_PER_ATB / BLOCKS_PER_FTB + MP_BITS_PER_BYTE * BLOCKS_PER_ATB * BYTES_PER_BLOCK);
     #else
-    MP_STATE_MEM(gc_alloc_table_byte_len) = total_byte_len / (1 + BITS_PER_BYTE / 2 * BYTES_PER_BLOCK);
+    MP_STATE_MEM(gc_alloc_table_byte_len) = total_byte_len / (1 + MP_BITS_PER_BYTE / 2 * BYTES_PER_BLOCK);
     #endif
 
     MP_STATE_MEM(gc_alloc_table_start) = (byte *)start;
diff --git a/py/mpconfig.h b/py/mpconfig.h
index 3c1ed28d80..3a0c5fb6e7 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -1535,8 +1535,9 @@ typedef double mp_float_t;
 #define BYTES_PER_WORD (sizeof(mp_uint_t))
 #endif
 
-#ifndef BITS_PER_BYTE
-#define BITS_PER_BYTE (8)
+// Number of bits in a byte
+#ifndef MP_BITS_PER_BYTE
+#define MP_BITS_PER_BYTE (8)
 #endif
 // mp_int_t value with most significant bit set
 #define WORD_MSBIT_HIGH (((mp_uint_t)1) << (BYTES_PER_WORD * 8 - 1))
diff --git a/py/objfloat.c b/py/objfloat.c
index 451609492e..5194dba51e 100644
--- a/py/objfloat.c
+++ b/py/objfloat.c
@@ -77,7 +77,7 @@ mp_int_t mp_float_hash(mp_float_t src) {
             // number may have a fraction; xor the integer part with the fractional part
             val = (frc >> (MP_FLOAT_FRAC_BITS - adj_exp))
                 ^ (frc & (((mp_float_uint_t)1 << (MP_FLOAT_FRAC_BITS - adj_exp)) - 1));
-        } else if ((unsigned int)adj_exp < BITS_PER_BYTE * sizeof(mp_int_t) - 1) {
+        } else if ((unsigned int)adj_exp < MP_BITS_PER_BYTE * sizeof(mp_int_t) - 1) {
             // the number is a (big) whole integer and will fit in val's signed-width
             val = (mp_int_t)frc << (adj_exp - MP_FLOAT_FRAC_BITS);
         } else {
diff --git a/py/objint.c b/py/objint.c
index 4619fb5751..00375d388e 100644
--- a/py/objint.c
+++ b/py/objint.c
@@ -121,7 +121,7 @@ STATIC mp_fp_as_int_class_t mp_classify_fp_as_int(mp_float_t val) {
         return MP_FP_CLASS_FIT_SMALLINT;
     }
     #if MICROPY_LONGINT_IMPL == MICROPY_LONGINT_IMPL_LONGLONG
-    if (e <= (((sizeof(long long) * BITS_PER_BYTE) + MP_FLOAT_EXP_BIAS - 2) << MP_FLOAT_EXP_SHIFT_I32)) {
+    if (e <= (((sizeof(long long) * MP_BITS_PER_BYTE) + MP_FLOAT_EXP_BIAS - 2) << MP_FLOAT_EXP_SHIFT_I32)) {
         return MP_FP_CLASS_FIT_LONGINT;
     }
     #endif
diff --git a/py/runtime.c b/py/runtime.c
index 2e2fa1d173..5d476a2764 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -387,7 +387,7 @@ mp_obj_t mp_binary_op(mp_binary_op_t op, mp_obj_t lhs, mp_obj_t rhs) {
                     if (rhs_val < 0) {
                         // negative shift not allowed
                         mp_raise_ValueError(MP_ERROR_TEXT("negative shift count"));
-                    } else if (rhs_val >= (mp_int_t)(sizeof(lhs_val) * BITS_PER_BYTE)
+                    } else if (rhs_val >= (mp_int_t)(sizeof(lhs_val) * MP_BITS_PER_BYTE)
                                || lhs_val > (MP_SMALL_INT_MAX >> rhs_val)
                                || lhs_val < (MP_SMALL_INT_MIN >> rhs_val)) {
                         // left-shift will overflow, so use higher precision integer
@@ -406,10 +406,10 @@ mp_obj_t mp_binary_op(mp_binary_op_t op, mp_obj_t lhs, mp_obj_t rhs) {
                         mp_raise_ValueError(MP_ERROR_TEXT("negative shift count"));
                     } else {
                         // standard precision is enough for right-shift
-                        if (rhs_val >= (mp_int_t)(sizeof(lhs_val) * BITS_PER_BYTE)) {
+                        if (rhs_val >= (mp_int_t)(sizeof(lhs_val) * MP_BITS_PER_BYTE)) {
                             // Shifting to big amounts is underfined behavior
                             // in C and is CPU-dependent; propagate sign bit.
-                            rhs_val = sizeof(lhs_val) * BITS_PER_BYTE - 1;
+                            rhs_val = sizeof(lhs_val) * MP_BITS_PER_BYTE - 1;
                         }
                         lhs_val >>= rhs_val;
                     }