diff --git a/src/core/window-props.c b/src/core/window-props.c
index b5883ad..4cabb1c 100644
--- a/src/core/window-props.c
+++ b/src/core/window-props.c
@@ -301,7 +301,7 @@ get_local_pid (MetaWindow *window)
   pid_t pid;
   XResClientIdSpec spec;
   long num_ids;
-  XResClientIdValue *client_ids;
+  XResClientIdValue *client_ids = NULL;
   long i;
 
   pid = -1;