diff --git a/src-input/builtins.yaml b/src-input/builtins.yaml
index b9aff659..1df317dc 100644
--- a/src-input/builtins.yaml
+++ b/src-input/builtins.yaml
@@ -1522,7 +1522,68 @@ objects:
           type: double
           bytes: "fff0000000000000"  # DBL_NEGATIVE_INFINITY
         attributes: ""
+      - key: "EPSILON"
+        value:
+          type: double
+          bytes: "3cb0000000000000"   # 3ff0000000000001 - 3ff0000000000000 = 3cb0000000000000
+        attributes: ""
+        es6: true
+        present_if: DUK_USE_ES6
+      - key: "MAX_SAFE_INTEGER"
+        value:
+          # >>> struct.pack('>d', 9007199254740991.0).encode('hex')
+          # '433fffffffffffff'
+          type: double
+          bytes: "433fffffffffffff"
+        attributes: ""
+        es6: true
+        present_if: DUK_USE_ES6
+      - key: "MIN_SAFE_INTEGER"
+        value:
+          # >>> struct.pack('>d', -9007199254740991.0).encode('hex')
+          # 'c33fffffffffffff'
+          type: double
+          bytes: "c33fffffffffffff"
+        attributes: ""
+        es6: true
+        present_if: DUK_USE_ES6
 
+      - key: "isFinite"
+        value:
+          type: function
+          native: duk_bi_number_check_shared
+          length: 1
+          magic: 0
+        attributes: "wc"
+        es6: true
+        present_if: DUK_USE_ES6
+      - key: "isInteger"
+        value:
+          type: function
+          native: duk_bi_number_check_shared
+          length: 1
+          magic: 1
+        attributes: "wc"
+        es6: true
+        present_if: DUK_USE_ES6
+      - key: "isNaN"
+        value:
+          type: function
+          native: duk_bi_number_check_shared
+          length: 1
+          magic: 2
+        attributes: "wc"
+        es6: true
+        present_if: DUK_USE_ES6
+      - key: "isSafeInteger"
+        value:
+          type: function
+          native: duk_bi_number_check_shared
+          length: 1
+          magic: 3
+        attributes: "wc"
+        es6: true
+        present_if: DUK_USE_ES6
       - key: "parseInt"  # Must map to the exactly same object as global parseInt()
         value:
           type: object
diff --git a/src-input/duk_bi_number.c b/src-input/duk_bi_number.c
index c687b056..c6788e95 100644
--- a/src-input/duk_bi_number.c
+++ b/src-input/duk_bi_number.c
@@ -237,4 +237,40 @@ DUK_INTERNAL duk_ret_t duk_bi_number_prototype_to_precision(duk_hthread *thr) {
 	return 1;
 }
 
+/*
+ *  ES2015 isFinite() etc
+ */
+
+#if defined(DUK_USE_ES6)
+DUK_INTERNAL duk_ret_t duk_bi_number_check_shared(duk_hthread *thr) {
+	duk_int_t magic;
+	duk_bool_t ret = 0;
+
+	if (duk_is_number(thr, 0)) {
+		duk_double_t d;
+
+		magic = duk_get_current_magic(thr);
+		d = duk_get_number(thr, 0);
+
+		switch (magic) {
+		case 0:  /* isFinite() */
+			ret = duk_double_is_finite(d);
+			break;
+		case 1:  /* isInteger() */
+			ret = duk_double_is_integer(d);
+			break;
+		case 2:  /* isNaN() */
+			ret = duk_double_is_nan(d);
+			break;
+		default:  /* isSafeInteger() */
+			DUK_ASSERT(magic == 3);
+			ret = duk_double_is_safe_integer(d);
+		}
+	}
+
+	duk_push_boolean(thr, ret);
+	return 1;
+}
+#endif  /* DUK_USE_ES6 */
+
 #endif  /* DUK_USE_NUMBER_BUILTIN */
diff --git a/src-input/duk_util.h b/src-input/duk_util.h
index 8934fe59..2600dcce 100644
--- a/src-input/duk_util.h
+++ b/src-input/duk_util.h
@@ -560,5 +560,8 @@ DUK_INTERNAL_DECL duk_double_t duk_double_trunc_towards_zero(duk_double_t x);
 DUK_INTERNAL_DECL duk_bool_t duk_double_same_sign(duk_double_t x, duk_double_t y);
 DUK_INTERNAL_DECL duk_double_t duk_double_fmin(duk_double_t x, duk_double_t y);
 DUK_INTERNAL_DECL duk_double_t duk_double_fmax(duk_double_t x, duk_double_t y);
+DUK_INTERNAL_DECL duk_bool_t duk_double_is_finite(duk_double_t x);
+DUK_INTERNAL_DECL duk_bool_t duk_double_is_integer(duk_double_t x);
+DUK_INTERNAL_DECL duk_bool_t duk_double_is_safe_integer(duk_double_t x);
 
 #endif  /* DUK_UTIL_H_INCLUDED */
diff --git a/src-input/duk_util_misc.c b/src-input/duk_util_misc.c
index aea3d009..01c019cf 100644
--- a/src-input/duk_util_misc.c
+++ b/src-input/duk_util_misc.c
@@ -403,3 +403,22 @@ DUK_INTERNAL duk_double_t duk_double_fmax(duk_double_t x, duk_double_t y) {
 	 */
 	return (x > y ? x : y);
 }
+
+DUK_INTERNAL duk_bool_t duk_double_is_finite(duk_double_t x) {
+	return !duk_double_is_nan_or_inf(x);
+}
+
+DUK_INTERNAL duk_bool_t duk_double_is_integer(duk_double_t x) {
+	if (duk_double_is_nan_or_inf(x)) {
+		return 0;
+	} else {
+		return duk_js_tointeger_number(x) == x;
+	}
+}
+
+DUK_INTERNAL duk_bool_t duk_double_is_safe_integer(duk_double_t x) {
+	/* >>> 2**53-1
+	 * 9007199254740991
+	 */
+	return duk_double_is_integer(x) && DUK_FABS(x) <= 9007199254740991.0;
+}