diff --git a/crypto/bn/div.c b/crypto/bn/div.c
index 2bf86de..8b0152e 100644
--- a/crypto/bn/div.c
+++ b/crypto/bn/div.c
@@ -362,7 +362,9 @@
      * BN_rshift() will overwrite it.
      */
     int neg = num->neg;
-    BN_rshift(rm, snum, norm_shift);
+    if (!BN_rshift(rm, snum, norm_shift)) {
+      goto err;
+    }
     if (!BN_is_zero(rm)) {
       rm->neg = neg;
     }
diff --git a/crypto/bn/gcd.c b/crypto/bn/gcd.c
index 789a094..3132c29 100644
--- a/crypto/bn/gcd.c
+++ b/crypto/bn/gcd.c
@@ -258,12 +258,8 @@
     goto err;
   }
 
-  BN_one(X);
   BN_zero(Y);
-  if (BN_copy(B, a) == NULL) {
-    goto err;
-  }
-  if (BN_copy(A, n) == NULL) {
+  if (!BN_one(X) || BN_copy(B, a) == NULL || BN_copy(A, n) == NULL) {
     goto err;
   }
   A->neg = 0;
@@ -570,12 +566,8 @@
     goto err;
   }
 
-  BN_one(X);
   BN_zero(Y);
-  if (BN_copy(B, a) == NULL) {
-    goto err;
-  }
-  if (BN_copy(A, n) == NULL) {
+  if (!BN_one(X) || BN_copy(B, a) == NULL || BN_copy(A, n) == NULL) {
     goto err;
   }
   A->neg = 0;
diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h
index cabc56d..8a9d686 100644
--- a/include/openssl/ssl.h
+++ b/include/openssl/ssl.h
@@ -1043,10 +1043,24 @@
 #define OPENSSL_NPN_NEGOTIATED 1
 #define OPENSSL_NPN_NO_OVERLAP 2
 
+/* SSL_CTX_set_alpn_protos sets the ALPN protocol list on |ctx| to |protos|.
+ * |protos| must be in wire-format (i.e. a series of non-empty, 8-bit
+ * length-prefixed strings). It returns zero on success and one on failure.
+ *
+ * WARNING: this function is dangerous because it breaks the usual return value
+ * convention. */
 OPENSSL_EXPORT int SSL_CTX_set_alpn_protos(SSL_CTX *ctx, const uint8_t *protos,
                                            unsigned protos_len);
+
+/* SSL_set_alpn_protos sets the ALPN protocol list on |ssl| to |protos|.
+ * |protos| must be in wire-format (i.e. a series of non-empty, 8-bit
+ * length-prefixed strings). It returns zero on success and one on failure.
+ *
+ * WARNING: this function is dangerous because it breaks the usual return value
+ * convention. */
 OPENSSL_EXPORT int SSL_set_alpn_protos(SSL *ssl, const uint8_t *protos,
                                        unsigned protos_len);
+
 OPENSSL_EXPORT void SSL_CTX_set_alpn_select_cb(
     SSL_CTX *ctx, int (*cb)(SSL *ssl, const uint8_t **out, uint8_t *outlen,
                             const uint8_t *in, unsigned int inlen, void *arg),
diff --git a/ssl/s3_both.c b/ssl/s3_both.c
index a34d221..ddfc1fe 100644
--- a/ssl/s3_both.c
+++ b/ssl/s3_both.c
@@ -296,7 +296,7 @@
   return ssl3_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
 }
 
-unsigned long ssl3_output_cert_chain(SSL *s, CERT_PKEY *cpk) {
+int ssl3_output_cert_chain(SSL *s, CERT_PKEY *cpk) {
   uint8_t *p;
   unsigned long l = 3 + SSL_HM_HEADER_LENGTH(s);
 
@@ -309,7 +309,7 @@
   l2n3(l, p);
   l += 3;
   ssl_set_handshake_header(s, SSL3_MT_CERTIFICATE, l);
-  return l + SSL_HM_HEADER_LENGTH(s);
+  return 1;
 }
 
 /* Obtain handshake message of message type |msg_type| (any if |msg_type| == -1),
diff --git a/ssl/s3_clnt.c b/ssl/s3_clnt.c
index c51ba6d..c6c2b42 100644
--- a/ssl/s3_clnt.c
+++ b/ssl/s3_clnt.c
@@ -1100,6 +1100,9 @@
        * initialized |sess_cert|. */
       if (s->session->sess_cert == NULL) {
         s->session->sess_cert = ssl_sess_cert_new();
+        if (s->session->sess_cert == NULL) {
+          return -1;
+        }
       }
 
       /* TODO(davidben): This should be reset in one place with the rest of the
@@ -1128,6 +1131,9 @@
     }
   } else {
     s->session->sess_cert = ssl_sess_cert_new();
+    if (s->session->sess_cert == NULL) {
+      return -1;
+    }
   }
 
   alg_k = s->s3->tmp.new_cipher->algorithm_mkey;
@@ -2182,8 +2188,10 @@
   }
 
   if (s->state == SSL3_ST_CW_CERT_C) {
-    s->state = SSL3_ST_CW_CERT_D;
-    ssl3_output_cert_chain(s, (s->s3->tmp.cert_req == 2) ? NULL : s->cert->key);
+    CERT_PKEY *cert_pkey = (s->s3->tmp.cert_req == 2) ? NULL : s->cert->key;
+    if (!ssl3_output_cert_chain(s, cert_pkey)) {
+      return -1;
+    }
   }
 
   /* SSL3_ST_CW_CERT_D */
diff --git a/ssl/s3_srvr.c b/ssl/s3_srvr.c
index 3f89558..c020b3a 100644
--- a/ssl/s3_srvr.c
+++ b/ssl/s3_srvr.c
@@ -2163,6 +2163,9 @@
 
   /* Filter out unsupported certificate types. */
   pkey = X509_get_pubkey(peer);
+  if (pkey == NULL) {
+    goto err;
+  }
   if (!(X509_certificate_type(peer, pkey) & EVP_PKT_SIGN) ||
       (pkey->type != EVP_PKEY_RSA && pkey->type != EVP_PKEY_EC)) {
     al = SSL_AD_UNSUPPORTED_CERTIFICATE;
@@ -2413,7 +2416,9 @@
       return 0;
     }
 
-    ssl3_output_cert_chain(s, cpk);
+    if (!ssl3_output_cert_chain(s, cpk)) {
+      return 0;
+    }
     s->state = SSL3_ST_SW_CERT_B;
   }
 
@@ -2683,6 +2688,9 @@
   BN_init(&y);
   sig.r = BN_new();
   sig.s = BN_new();
+  if (sig.r == NULL || sig.s == NULL) {
+    goto err;
+  }
 
   p = CBS_data(&extension);
   if (BN_bin2bn(p + 0, 32, &x) == NULL ||
diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
index 348e2a5..de57330 100644
--- a/ssl/ssl_lib.c
+++ b/ssl/ssl_lib.c
@@ -1677,11 +1677,6 @@
   ctx->next_proto_select_cb_arg = arg;
 }
 
-/* SSL_CTX_set_alpn_protos sets the ALPN protocol list on |ctx| to |protos|.
- * |protos| must be in wire-format (i.e. a series of non-empty, 8-bit
- * length-prefixed strings).
- *
- * Returns 0 on success. */
 int SSL_CTX_set_alpn_protos(SSL_CTX *ctx, const uint8_t *protos,
                             unsigned protos_len) {
   if (ctx->alpn_client_proto_list) {
@@ -1697,11 +1692,6 @@
   return 0;
 }
 
-/* SSL_set_alpn_protos sets the ALPN protocol list on |ssl| to |protos|.
- * |protos| must be in wire-format (i.e. a series of non-empty, 8-bit
- * length-prefixed strings).
- *
- * Returns 0 on success. */
 int SSL_set_alpn_protos(SSL *ssl, const uint8_t *protos, unsigned protos_len) {
   if (ssl->alpn_client_proto_list) {
     OPENSSL_free(ssl->alpn_client_proto_list);
diff --git a/ssl/ssl_locl.h b/ssl/ssl_locl.h
index d63ddda..c7abe79 100644
--- a/ssl/ssl_locl.h
+++ b/ssl/ssl_locl.h
@@ -758,7 +758,7 @@
 int ssl3_cert_verify_mac(SSL *s, int md_nid, uint8_t *p);
 void ssl3_finish_mac(SSL *s, const uint8_t *buf, int len);
 void ssl3_free_digest_list(SSL *s);
-unsigned long ssl3_output_cert_chain(SSL *s, CERT_PKEY *cpk);
+int ssl3_output_cert_chain(SSL *s, CERT_PKEY *cpk);
 const SSL_CIPHER *ssl3_choose_cipher(
     SSL *ssl, STACK_OF(SSL_CIPHER) * clnt,
     struct ssl_cipher_preference_list_st *srvr);
diff --git a/ssl/t1_enc.c b/ssl/t1_enc.c
index fd0223d..a3d8925 100644
--- a/ssl/t1_enc.c
+++ b/ssl/t1_enc.c
@@ -737,7 +737,10 @@
   }
 
   EVP_MD_CTX_init(&ctx);
-  EVP_MD_CTX_copy_ex(&ctx, d);
+  if (!EVP_MD_CTX_copy_ex(&ctx, d)) {
+    EVP_MD_CTX_cleanup(&ctx);
+    return 0;
+  }
   EVP_DigestFinal_ex(&ctx, out, &ret);
   EVP_MD_CTX_cleanup(&ctx);
 
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index 19e52a4..967dad7 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -2584,7 +2584,10 @@
     if (s->s3->handshake_dgst[i] == NULL) {
       continue;
     }
-    EVP_MD_CTX_copy_ex(&ctx, s->s3->handshake_dgst[i]);
+    if (!EVP_MD_CTX_copy_ex(&ctx, s->s3->handshake_dgst[i])) {
+      EVP_MD_CTX_cleanup(&ctx);
+      return 0;
+    }
     EVP_DigestFinal_ex(&ctx, temp_digest, &temp_digest_len);
     EVP_DigestUpdate(md, temp_digest, temp_digest_len);
   }
diff --git a/ssl/test/bssl_shim.cc b/ssl/test/bssl_shim.cc
index 90d142a..e552065 100644
--- a/ssl/test/bssl_shim.cc
+++ b/ssl/test/bssl_shim.cc
@@ -363,10 +363,14 @@
     case SSL_ERROR_WANT_WRITE:
       AsyncBioAllowWrite(async, 1);
       return 1;
-    case SSL_ERROR_WANT_CHANNEL_ID_LOOKUP:
-      GetTestState(ssl)->channel_id =
-          LoadPrivateKey(GetConfigPtr(ssl)->send_channel_id);
+    case SSL_ERROR_WANT_CHANNEL_ID_LOOKUP: {
+      ScopedEVP_PKEY pkey = LoadPrivateKey(GetConfigPtr(ssl)->send_channel_id);
+      if (!pkey) {
+        return 0;
+      }
+      GetTestState(ssl)->channel_id = std::move(pkey);
       return 1;
+    }
     case SSL_ERROR_WANT_X509_LOOKUP:
       GetTestState(ssl)->cert_ready = true;
       return 1;
@@ -455,12 +459,17 @@
       }
     }
   }
-  if (!config->host_name.empty()) {
-    SSL_set_tlsext_host_name(ssl.get(), config->host_name.c_str());
+  if (!config->host_name.empty() &&
+      !SSL_set_tlsext_host_name(ssl.get(), config->host_name.c_str())) {
+    BIO_print_errors_fp(stdout);
+    return 1;
   }
-  if (!config->advertise_alpn.empty()) {
-    SSL_set_alpn_protos(ssl.get(), (const uint8_t *)config->advertise_alpn.data(),
-                        config->advertise_alpn.size());
+  if (!config->advertise_alpn.empty() &&
+      SSL_set_alpn_protos(ssl.get(),
+                          (const uint8_t *)config->advertise_alpn.data(),
+                          config->advertise_alpn.size()) != 0) {
+    BIO_print_errors_fp(stdout);
+    return 1;
   }
   if (!config->psk.empty()) {
     SSL_set_psk_client_callback(ssl.get(), PskClientCallback);
diff --git a/ssl/test/packeted_bio.cc b/ssl/test/packeted_bio.cc
index e003985..8f4f3de 100644
--- a/ssl/test/packeted_bio.cc
+++ b/ssl/test/packeted_bio.cc
@@ -186,6 +186,9 @@
 
 ScopedBIO PacketedBioCreate(OPENSSL_timeval *out_timeout) {
   ScopedBIO bio(BIO_new(&g_packeted_bio_method));
+  if (!bio) {
+    return nullptr;
+  }
   bio->ptr = out_timeout;
   return bio;
 }