diff --git a/sys/sys/md5.h b/sys/sys/md5.h
index 311724e1daf9..e98b7afb6ef7 100644
--- a/sys/sys/md5.h
+++ b/sys/sys/md5.h
@@ -27,6 +27,11 @@ documentation and/or software.
 
 #ifndef _SYS_MD5_H_
 #define _SYS_MD5_H_
+
+#define MD5_BLOCK_LENGTH		64
+#define MD5_DIGEST_LENGTH		16
+#define MD5_DIGEST_STRING_LENGTH	(MD5_DIGEST_LENGTH * 2 + 1)
+
 /* MD5 context. */
 typedef struct MD5Context {
   u_int32_t state[4];	/* state (ABCD) */