--- a/generic/bltObjConfig.c	2022-08-04 10:42:54.705864029 +0200
+++ b/generic/bltObjConfig.c	2022-08-04 10:44:02.681005365 +0200
@@ -1803,11 +1803,11 @@
             fprintf(stderr, "Blt_ConfigTypes changed\n");
         }
         if (stype == BLT_CONFIG_CUSTOM) {
-            extern Blt_CustomOption bltDistanceOption;
-            extern Blt_CustomOption bltPositiveDistanceOption;
+            extern Tk_CustomOption bltDistanceOption;
+            extern Tk_CustomOption bltPositiveDistanceOption;
 
-            if (specPtr->customPtr == &bltDistanceOption ||
-                specPtr->customPtr == &bltPositiveDistanceOption
+            if (specPtr->customPtr == (Blt_CustomOption *)&bltDistanceOption ||
+                specPtr->customPtr == (Blt_CustomOption *)&bltPositiveDistanceOption
             ) {
                 stype = BLT_CONFIG_PIXELS;
             }