--- a/generic/Window.c	2023-01-17 19:39:55.697886490 +0100
+++ b/generic/Window.c	2023-01-17 19:41:15.619618094 +0100
@@ -350,7 +350,7 @@
 #endif /* ifdef _WIN32 */
 
    /* Reset externalwindow */
-   wind->externalwindow = NULL;
+   wind->externalwindow = 0;
 }
 
 
@@ -384,7 +384,7 @@
   wind->connection_anchor = TK_ANCHOR_SW;
   wind->win = NULL;
   wind->windowtitle = NULL;
-  wind->externalwindow = NULL;
+  wind->externalwindow = 0;
   
   return TCL_OK;
 }
@@ -407,7 +407,7 @@
    */
   wind->win = NULL;
   wind->windowtitle = NULL;
-  wind->externalwindow = NULL;
+  wind->externalwindow = 0;
 }
 
 
