diff --git a/ext/digest/md5/md5init.c b/ext/digest/md5/md5init.c
index db9298cbfc..bcd332d648 100644
--- a/ext/digest/md5/md5init.c
+++ b/ext/digest/md5/md5init.c
@@ -2,7 +2,7 @@
 /* $Id$ */
 
 #include "digest.h"
-#if defined(MD5_USE__OPENSSL)
+#if defined(MD5_USE_OPENSSL)
 #include "md5ossl.h"
 #elif defined(MD5_USE_COMMONDIGEST)
 #include "md5cc.h"