diff --git a/c/coreslam.c b/c/coreslam.c
index b6dd380..35ae1fb 100644
--- a/c/coreslam.c
+++ b/c/coreslam.c
@@ -439,6 +439,8 @@ scan_update(
         double  velocities_dxy_mm,
         double  velocities_dtheta_degrees)
 {    
+    printf("%p %d\n", lidar_angles_deg, scan_size);
+
     /* Take velocity into account */
     int degrees_per_second = (int)(scan->rate_hz * 360);
     double horz_mm = velocities_dxy_mm / degrees_per_second;
diff --git a/python/pybreezyslam.c b/python/pybreezyslam.c
index 9367030..ca66f9f 100644
--- a/python/pybreezyslam.c
+++ b/python/pybreezyslam.c
@@ -353,7 +353,7 @@ Scan_update(Scan *self, PyObject *args, PyObject *kwds)
     // Update the scan
     scan_update(
             &self->scan, 
-            NULL,
+            (py_scan_angles_degrees != Py_None) ? self->lidar_angles_deg :NULL,
             self->lidar_distances_mm, 
             PyList_Size(py_lidar),
             hole_width_mm,