diff --git a/include/rjp_internal.h b/include/rjp_internal.h
index e9b0e56..14bf5a6 100644
--- a/include/rjp_internal.h
+++ b/include/rjp_internal.h
@@ -20,6 +20,7 @@
 #define RJP_INTERNAL_H
 
 #include "rjp.h"
+#include "config.h"
 #include <stdio.h>
 
 #ifdef __GNUC__
@@ -30,7 +31,7 @@
 
 #define UNUSED_VARIABLE(thing) (void)(thing)
 
-#ifdef RJP_DIAGNOSTICS
+#ifdef RJP_ENABLE_DIAGNOSTICS
 #define DIAG_PRINT(...) fprintf(__VA_ARGS__)
 #else
 #define DIAG_PRINT(...) irjp_ignore_unused(__VA_ARGS__)