diff --git a/randr/rrcrtc.c b/randr/rrcrtc.c
index 76365919a..5d404e84b 100644
--- a/randr/rrcrtc.c
+++ b/randr/rrcrtc.c
@@ -281,7 +281,7 @@ crtc_bounds(RRCrtcPtr crtc, int *left, int *right, int *top, int *bottom)
     *left = crtc->x;
     *top = crtc->y;
 
-    switch (crtc->rotation) {
+    switch (crtc->rotation & 0xf) {
     case RR_Rotate_0:
     case RR_Rotate_180:
     default: