--- a/src/misc_gui.cpp	Tue Feb 13 09:54:37 2007 +0000
+++ b/src/misc_gui.cpp	Tue Feb 13 10:17:24 2007 +0000
@@ -498,7 +498,7 @@
 		COPY_IN_DPARAM(0, _errmsg_decode_params, lengthof(_errmsg_decode_params));
 		DrawWindowWidgets(w);
 		COPY_IN_DPARAM(0, _errmsg_decode_params, lengthof(_errmsg_decode_params));
-		if (!IsWindowOfPrototype(w, _errmsg_face_widgets)) {
+		if (!w->IsWindowOfPrototype(_errmsg_face_widgets)) {
 			DrawStringMultiCenter(
 				120,
 				(_errmsg_message_1 == INVALID_STRING_ID ? 25 : 15),