diff --git a/cfg/motif.cfg b/cfg/motif.cfg
index c0708afcf..4654fac54 100644
--- a/cfg/motif.cfg
+++ b/cfg/motif.cfg
@@ -281,6 +281,15 @@
       <not-uninit/>
     </arg>
   </function>
+  <!-- https://www.x.org/releases/X11R7.7/doc/libX11/libX11/libX11.html#id2656808 -->
+  <!-- XFree(void *data); -->
+  <function name="XFree">
+    <noreturn>false</noreturn>
+    <arg nr="1">
+      <not-null/>
+      <not-bool/>
+    </arg>
+  </function>
   <function name="XtDatabase">
     <noreturn>false</noreturn>
     <leak-ignore/>