diff --git a/src/post_modules/GL/gen.pike b/src/post_modules/GL/gen.pike
index 9c03fee07805fad5a17e865afadbc19022043f11..04a5254f069095e73d23423848285ab8cb9e2e49 100755
--- a/src/post_modules/GL/gen.pike
+++ b/src/post_modules/GL/gen.pike
@@ -425,7 +425,8 @@ string gen()
     res += "  add_function_constant(\""+f+"\", f_"+f+",\n\t\t\t\"function("+
       prot[f]+")\", OPT_SIDE_EFFECT);\n";
   foreach(sort(indices(constants)), string co)
-    res += "  add_integer_constant(\""+co+"\", "+constants[co]+", 0);\n";
+    res += "  add_integer_constant(\""+co+"\", "+
+           (string)constants[co]+", 0);\n";
   res += "  post_init();\n";
   res += "}\n";
   return res;