diff --git a/crypto/crypto_test.cc b/crypto/crypto_test.cc
index 52a51bc736..0f38923402 100644
--- a/crypto/crypto_test.cc
+++ b/crypto/crypto_test.cc
@@ -86,10 +86,18 @@ TEST(CryptoTest, OPENSSL_hexstr2buf) {
     // The longest test case we have is currently 4 bytes long
     size_t expected_answer_len = OPENSSL_strnlen(test_case[1], 5);
     unsigned char *buf = OPENSSL_hexstr2buf(test_value, &actual_answer_len);
+    ASSERT_TRUE(buf != nullptr);
     EXPECT_EQ(expected_answer_len, actual_answer_len);
     EXPECT_EQ(0, OPENSSL_memcmp(buf, expected_answer, expected_answer_len));
     OPENSSL_free(buf);
   }
+
+  // Test failure modes
+  size_t actual_answer_len = 0;
+  EXPECT_FALSE(OPENSSL_hexstr2buf("a", &actual_answer_len));
+  EXPECT_FALSE(OPENSSL_hexstr2buf(NULL, &actual_answer_len));
+  EXPECT_FALSE(OPENSSL_hexstr2buf("ab", nullptr));
+  EXPECT_FALSE(OPENSSL_hexstr2buf("ag", &actual_answer_len));
 }
 
 #if defined(BORINGSSL_FIPS_COUNTERS)
diff --git a/crypto/evp_extra/p_x25519.c b/crypto/evp_extra/p_x25519.c
index ee78b24fc7..197e1f8297 100644
--- a/crypto/evp_extra/p_x25519.c
+++ b/crypto/evp_extra/p_x25519.c
@@ -106,7 +106,7 @@ const EVP_PKEY_METHOD x25519_pkey_meth = {
     pkey_x25519_derive,
     NULL /* paramgen */,
     pkey_x25519_ctrl,
-    NULL,
+    NULL, /* ctrl_str */
     NULL /* keygen deterministic */,
     NULL /* encapsulate deterministic */,
     NULL /* encapsulate */,