diff --git a/dlls/advapi32/crypt.c b/dlls/advapi32/crypt.c
index ba38f6581fb..94ac6673b4b 100644
--- a/dlls/advapi32/crypt.c
+++ b/dlls/advapi32/crypt.c
@@ -756,6 +756,7 @@ BOOL WINAPI CryptDeriveKey (HCRYPTPROV hProv, ALG_ID Algid, HCRYPTHASH hBaseData
 
 	/* CSP error! */
 	CRYPT_Free(key);
+	*phKey = 0;
 	return FALSE;
 }