--- wmctrl-1.07.orig/main.c
+++ wmctrl-1.07/main.c
@@ -1425,6 +1425,16 @@
      *
      * long_length = Specifies the length in 32-bit multiples of the
      *               data to be retrieved.
+     *
+     * NOTE:  see 
+     * http://mail.gnome.org/archives/wm-spec-list/2003-March/msg00067.html
+     * In particular:
+     *
+     * 	When the X window system was ported to 64-bit architectures, a
+     * rather peculiar design decision was made. 32-bit quantities such
+     * as Window IDs, atoms, etc, were kept as longs in the client side
+     * APIs, even when long was changed to 64 bits.
+     *
      */
     if (XGetWindowProperty(disp, win, xa_prop_name, 0, MAX_PROPERTY_VALUE_LEN / 4, False,
             xa_prop_type, &xa_ret_type, &ret_format,     
@@ -1441,6 +1451,8 @@
 
     /* null terminate the result to make string handling easier */
     tmp_size = (ret_format / 8) * ret_nitems;
+    /* Correct 64 Architecture implementation of 32 bit data */
+    if(ret_format==32) tmp_size *= sizeof(long)/4;
     ret = g_malloc(tmp_size + 1);
     memcpy(ret, ret_prop, tmp_size);
     ret[tmp_size] = '\0';