diff --git a/python/port/mod/turtle/turtle.cpp b/python/port/mod/turtle/turtle.cpp
index d580e7007..8d33928ec 100644
--- a/python/port/mod/turtle/turtle.cpp
+++ b/python/port/mod/turtle/turtle.cpp
@@ -73,7 +73,7 @@ void Turtle::left(mp_float_t angle) {
 
 void Turtle::circle(mp_int_t radius, mp_float_t angle) {
   mp_float_t oldHeading = heading();
-  mp_float_t length = (angle > 0 ? 1 : -1) * angle * k_headingScale * radius;
+  mp_float_t length = (angle > 0 ? 1 : -1) * angle * k_headingScale * (radius > 0 ? 1 : -1) * radius;
   if (length > 1) {
     for (int i = 1; i < length; i++) {
       mp_float_t progress = i / length;
@@ -82,7 +82,7 @@ void Turtle::circle(mp_int_t radius, mp_float_t angle) {
         // Keyboard interruption. Return now to let MicroPython process it.
         return;
       }
-      setHeadingPrivate(oldHeading+angle*progress);
+      setHeadingPrivate(oldHeading+angle*progress*((radius>0) ? 1 : -1));
     }
     forward(1);
     setHeading(oldHeading+angle);