diff --git a/lib/modules/Process.pmod b/lib/modules/Process.pmod
index 65a407ecd6239c2622e1b76b860f43fc854c2929..0b8c8d620505e7c693de555110ba49a962bf0f85 100644
--- a/lib/modules/Process.pmod
+++ b/lib/modules/Process.pmod
@@ -456,7 +456,10 @@ Process spawn_pike(array(string) argv, void|mapping(string:mixed) options)
     if(options && options->add_predefines)
     {
       foreach (master()->predefines; string key; string value)
-        res+=({"-D" + key + "=" + value});
+	if( stringp( value ) )
+	  res+=({"-D" + key + "=" + value});
+	else if( intp( value ) )
+	  res+=({"-D" + key });
     }
     if(options && options->add_program_path)
     {