diff --git a/libcscreensaver/cs-screen-x11.c b/libcscreensaver/cs-screen-x11.c
index 068788d1..98029fb6 100644
--- a/libcscreensaver/cs-screen-x11.c
+++ b/libcscreensaver/cs-screen-x11.c
@@ -416,7 +416,7 @@ is_full_change (CsScreen *screen)
 {
     // Check to see if the union of monitor rects is the same size as the screen
 
-    GdkRectangle total_monitors;
+    GdkRectangle total_monitors = {0};
     gint i;
     gboolean same;