diff --git a/lib/roken/snprintf.c b/lib/roken/snprintf.c
index 6c940caea..2ecf8c23a 100644
--- a/lib/roken/snprintf.c
+++ b/lib/roken/snprintf.c
@@ -65,7 +65,7 @@ struct snprintf_state {
     /* XXX - methods */
 };
 
-#if TEST_SNPRINTF
+#if defined(TEST_SNPRINTF)
 #include "snprintf-test.h"
 #endif /* TEST_SNPRINTF */