diff --git a/lib/hcrypto/rand-fortuna.c b/lib/hcrypto/rand-fortuna.c
index 313b86f83..74ba12396 100644
--- a/lib/hcrypto/rand-fortuna.c
+++ b/lib/hcrypto/rand-fortuna.c
@@ -336,7 +336,7 @@ add_entropy(FState * st, const unsigned char *data, unsigned len)
 	st->pool0_bytes += len;
 
     memset_s(hash, sizeof(hash), 0, sizeof(hash));
-    memset_s(&md, sizeof(hash), 0, sizeof(md));
+    memset_s(&md, sizeof(md), 0, sizeof(md));
 }
 
 /*