diff --git a/src/Peer.cpp b/src/Peer.cpp
index 4b1a4f5615..8917c96b47 100644
--- a/src/Peer.cpp
+++ b/src/Peer.cpp
@@ -727,7 +727,7 @@ void Peer::getSessionCookie(std::string& strDst)
 
 	SHA512(s1, l1, sha1);
 	SHA512(s2, l2, sha2);
-	if (memcmp(s1, s2, sizeof(sha1))
+	if (memcmp(s1, s2, sizeof(sha1)) == 0)
 		throw std::runtime_errror("Identical finished messages");
 
 	for (int i = 0; i < sizeof(sha1); ++i)