diff --git a/src/lib/ecore_x/xlib/ecore_x_window_prop.c b/src/lib/ecore_x/xlib/ecore_x_window_prop.c
index 535c521941..286cdfcdba 100644
--- a/src/lib/ecore_x/xlib/ecore_x_window_prop.c
+++ b/src/lib/ecore_x/xlib/ecore_x_window_prop.c
@@ -160,7 +160,7 @@ ecore_x_window_prop_xid_set(Ecore_X_Window win,
    unsigned int i;
 
    LOGFN(__FILE__, __LINE__, __FUNCTION__);
-   pl = malloc(num * sizeof(long));
+   pl = malloc(num * sizeof(unsigned long));
    if (!pl)
      return;