diff --git a/src/os_dos.h b/src/os_dos.h
index 0edc3e0..bb8b308 100644
--- a/src/os_dos.h
+++ b/src/os_dos.h
@@ -125,6 +125,7 @@
 
 #define DFLT_ERRORFILE		"errors.err"
 #define DFLT_RUNTIMEPATH	"$HOME/vimfiles,$VIM/vimfiles,$VIMRUNTIME,$VIM/vimfiles/after,$HOME/vimfiles/after"
+#define CLEAN_RUNTIMEPATH	"$VIM/vimfiles,$VIMRUNTIME,$VIM/vimfiles/after"
 
 #define CASE_INSENSITIVE_FILENAME   /* ignore case when comparing file names */
 #define SPACE_IN_FILENAME