diff --git a/tests/unittests/torture_keyfiles.c b/tests/unittests/torture_keyfiles.c
index 59a4f5ee..114f42fa 100644
--- a/tests/unittests/torture_keyfiles.c
+++ b/tests/unittests/torture_keyfiles.c
@@ -104,7 +104,7 @@ static int teardown(void **state)
 
 static void torture_pubkey_from_file(void **state) {
     ssh_session session = *state;
-    ssh_string pubkey;
+    ssh_string pubkey = NULL;
     int type, rc;
 
     rc = ssh_try_publickey_from_file(session, LIBSSH_RSA_TESTKEY, &pubkey, &type);