diff --git a/src/window.c b/src/window.c
index a86f77a2..bd4e2719 100644
--- a/src/window.c
+++ b/src/window.c
@@ -244,6 +244,7 @@ void window_update_role(i3Window *win, xcb_get_property_reply_t *prop, bool befo
  */
 void window_update_type(i3Window *window, xcb_get_property_reply_t *reply) {
     xcb_atom_t new_type = xcb_get_preferred_window_type(reply);
+    free(reply);
     if (new_type == XCB_NONE) {
         DLOG("cannot read _NET_WM_WINDOW_TYPE from window.\n");
         return;