diff --git a/library/md4.c b/library/md4.c
index 251e63f..564a7f9 100644
--- a/library/md4.c
+++ b/library/md4.c
@@ -357,6 +357,15 @@
 }
 
 /*
+ * MD4 HMAC context reset
+ */
+void md4_hmac_reset( md4_context *ctx )
+{
+    md4_starts( ctx );
+    md4_update( ctx, ctx->ipad, 64 );
+}
+
+/*
  * output = HMAC-MD4( hmac key, input buffer )
  */
 void md4_hmac( const unsigned char *key, int keylen,