diff --git a/src/cairo-gstate.c b/src/cairo-gstate.c
index 1d706114e..0c6b2170f 100644
--- a/src/cairo-gstate.c
+++ b/src/cairo-gstate.c
@@ -663,7 +663,10 @@ _cairo_gstate_rotate (cairo_gstate_t *gstate, double angle)
 {
     cairo_matrix_t tmp;
 
-    if (! (angle * angle > 0.)) /* check for NaNs */
+    if (angle == 0.)
+	return CAIRO_STATUS_SUCCESS;
+
+    if (! (angle * angle >= 0.)) /* check for NaNs */
 	return _cairo_error (CAIRO_STATUS_INVALID_MATRIX);
 
     _cairo_gstate_unset_scaled_font (gstate);