diff --git a/py/objfloat.c b/py/objfloat.c
index 2ea9947fe..4db1bb89e 100644
--- a/py/objfloat.c
+++ b/py/objfloat.c
@@ -161,8 +161,7 @@ STATIC mp_obj_t float_unary_op(mp_unary_op_t op, mp_obj_t o_in) {
         case MP_UNARY_OP_POSITIVE: return o_in;
         case MP_UNARY_OP_NEGATIVE: return mp_obj_new_float(-val);
         case MP_UNARY_OP_ABS: {
-            // TODO check for NaN etc
-            if (val < 0) {
+            if (signbit(val)) {
                 return mp_obj_new_float(-val);
             } else {
                 return o_in;
diff --git a/tests/float/builtin_float_abs.py b/tests/float/builtin_float_abs.py
new file mode 100644
index 000000000..c0935c6ee
--- /dev/null
+++ b/tests/float/builtin_float_abs.py
@@ -0,0 +1,13 @@
+# test builtin abs function with float args
+
+for val in (
+    '1.0',
+    '-1.0',
+    '0.0',
+    '-0.0',
+    'nan',
+    '-nan',
+    'inf',
+    '-inf',
+    ):
+    print(val, abs(float(val)))