diff -Naur src.orig/wmgeneral.h src/wmgeneral.h
--- src.orig/wmgeneral.h	2002-10-19 11:33:41.000000000 +0200
+++ src/wmgeneral.h	2020-03-01 16:22:30.891485480 +0100
@@ -36,7 +36,7 @@
  /* Global variable */
 /*******************/
 
-Display		*display;
+extern Display		*display;
 
   /***********************/
  /* Function Prototypes */
diff -Naur src.orig/wmpuzzle.c src/wmpuzzle.c
--- src.orig/wmpuzzle.c	2013-06-27 20:42:26.000000000 +0200
+++ src/wmpuzzle.c	2020-03-01 16:22:28.716484905 +0100
@@ -41,6 +41,8 @@
 int blank      = 15,
 	puzzle[16] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
 
+Display		*display;
+
 int main(int argc, char *argv[])
 {
 	int n,