diff --git a/lib/mprintf.c b/lib/mprintf.c
index 475afb770b..543a39f150 100644
--- a/lib/mprintf.c
+++ b/lib/mprintf.c
@@ -39,7 +39,7 @@
 #include <string.h>
 
 #if defined(DJGPP) && (DJGPP_MINOR < 4)
-#undef CURLDEBUG  /* don't use x_was_used() here */
+#undef _MPRINTF_REPLACE /* don't use x_was_used() here */
 #endif
 
 #include <curl/mprintf.h>