diff --git a/RSA.xs b/RSA.xs
index 75cad1a..41bd247 100644
--- a/RSA.xs
+++ b/RSA.xs
@@ -657,9 +657,9 @@ _new_key_from_parameters(proto, n, e, d, p, q)
         int status = EVP_PKEY_fromdata(pctx, &rsa, EVP_PKEY_KEYPAIR, params);
         THROW( status > 0 && rsa != NULL );
         EVP_PKEY_CTX* test_ctx = EVP_PKEY_CTX_new_from_pkey(NULL, rsa, NULL);
-        int check_ok = EVP_PKEY_check(test_ctx);
+        int check_ok = (test_ctx != NULL && EVP_PKEY_check(test_ctx) == 1);
         EVP_PKEY_CTX_free(test_ctx);
-        THROW(check_ok == 1);
+        THROW(check_ok);
 #else
         THROW(RSA_set0_crt_params(rsa, dmp1, dmq1, iqmp));
 #endif