diff --git a/geoviews/operation/projection.py b/geoviews/operation/projection.py
index 22e5a835..f1ddc4f9 100644
--- a/geoviews/operation/projection.py
+++ b/geoviews/operation/projection.py
@@ -196,8 +196,8 @@ def _process_element(self, element):
         new_data[xdim.name] = coordinates[mask, 0]
         new_data[ydim.name] = coordinates[mask, 1]
         datatype = [element.interface.datatype]+element.datatype
-        us = np.sin(ang) * ms
-        vs = np.cos(ang) * ms
+        us = np.cos(ang) * ms
+        vs = np.sin(ang) * ms
         ut, vt = self.p.projection.transform_vectors(element.crs, xs, ys, us, vs)
         with np.errstate(divide='ignore', invalid='ignore'):
             angle = np.arctan2(vt, ut)