diff --git a/include/openssl/pem.h b/include/openssl/pem.h
index ae6c23c0..4868e12f 100644
--- a/include/openssl/pem.h
+++ b/include/openssl/pem.h
@@ -125,7 +125,7 @@ extern "C" {
 #define IMPLEMENT_PEM_read_fp(name, type, str, asn1) \
 OPENSSL_EXPORT type *PEM_read_##name(FILE *fp, type **x, pem_password_cb *cb, void *u)\
 { \
-return PEM_ASN1_read((d2i_of_void *)d2i_##asn1, str,fp,(void **)x,cb,u); \
+return (type *)PEM_ASN1_read((d2i_of_void *)d2i_##asn1, str,fp,(void **)x,cb,u); \
 } 
 
 #define IMPLEMENT_PEM_write_fp(name, type, str, asn1) \
@@ -161,7 +161,7 @@ OPENSSL_EXPORT int PEM_write_##name(FILE *fp, type *x, const EVP_CIPHER *enc, \
 #define IMPLEMENT_PEM_read_bio(name, type, str, asn1) \
 OPENSSL_EXPORT type *PEM_read_bio_##name(BIO *bp, type **x, pem_password_cb *cb, void *u)\
 { \
-return PEM_ASN1_read_bio((d2i_of_void *)d2i_##asn1, str,bp,(void **)x,cb,u); \
+return (type *)PEM_ASN1_read_bio((d2i_of_void *)d2i_##asn1, str,bp,(void **)x,cb,u); \
 }
 
 #define IMPLEMENT_PEM_write_bio(name, type, str, asn1) \
diff --git a/ssl/CMakeLists.txt b/ssl/CMakeLists.txt
index 0c09443d..94a1741c 100644
--- a/ssl/CMakeLists.txt
+++ b/ssl/CMakeLists.txt
@@ -3,21 +3,21 @@ include_directories(../include)
 add_library(
   ssl
 
-  bio_ssl.c
-  custom_extensions.c
-  d1_both.c
-  d1_lib.c
-  d1_pkt.c
-  d1_srtp.c
-  dtls_method.c
-  dtls_record.c
+  bio_ssl.cc
+  custom_extensions.cc
+  d1_both.cc
+  d1_lib.cc
+  d1_pkt.cc
+  d1_srtp.cc
+  dtls_method.cc
+  dtls_record.cc
   handshake_client.c
   handshake_server.c
-  s3_both.c
-  s3_lib.c
-  s3_pkt.c
+  s3_both.cc
+  s3_lib.cc
+  s3_pkt.cc
   ssl_aead_ctx.c
-  ssl_asn1.c
+  ssl_asn1.cc
   ssl_buffer.c
   ssl_cert.c
   ssl_cipher.c
@@ -30,7 +30,7 @@ add_library(
   ssl_stat.c
   ssl_transcript.c
   ssl_versions.c
-  ssl_x509.c
+  ssl_x509.cc
   t1_enc.c
   t1_lib.c
   tls_method.c
diff --git a/ssl/bio_ssl.c b/ssl/bio_ssl.cc
similarity index 94%
rename from ssl/bio_ssl.c
rename to ssl/bio_ssl.cc
index ad8f5d8f..61afee56 100644
--- a/ssl/bio_ssl.c
+++ b/ssl/bio_ssl.cc
@@ -12,8 +12,12 @@
 #include <openssl/bio.h>
 
 
+static SSL *get_ssl(BIO *bio) {
+  return reinterpret_cast<SSL *>(bio->ptr);
+}
+
 static int ssl_read(BIO *bio, char *out, int outl) {
-  SSL *ssl = bio->ptr;
+  SSL *ssl = get_ssl(bio);
   if (ssl == NULL) {
     return 0;
   }
@@ -53,7 +57,7 @@ static int ssl_read(BIO *bio, char *out, int outl) {
 }
 
 static int ssl_write(BIO *bio, const char *out, int outl) {
-  SSL *ssl = bio->ptr;
+  SSL *ssl = get_ssl(bio);
   if (ssl == NULL) {
     return 0;
   }
@@ -87,7 +91,7 @@ static int ssl_write(BIO *bio, const char *out, int outl) {
 }
 
 static long ssl_ctrl(BIO *bio, int cmd, long num, void *ptr) {
-  SSL *ssl = bio->ptr;
+  SSL *ssl = get_ssl(bio);
   if (ssl == NULL && cmd != BIO_C_SET_SSL) {
     return 0;
   }
@@ -134,7 +138,7 @@ static int ssl_new(BIO *bio) {
 }
 
 static int ssl_free(BIO *bio) {
-  SSL *ssl = bio->ptr;
+  SSL *ssl = get_ssl(bio);
 
   if (ssl == NULL) {
     return 1;
@@ -149,7 +153,7 @@ static int ssl_free(BIO *bio) {
 }
 
 static long ssl_callback_ctrl(BIO *bio, int cmd, bio_info_cb fp) {
-  SSL *ssl = bio->ptr;
+  SSL *ssl = get_ssl(bio);
   if (ssl == NULL) {
     return 0;
   }
diff --git a/ssl/custom_extensions.c b/ssl/custom_extensions.cc
similarity index 98%
rename from ssl/custom_extensions.c
rename to ssl/custom_extensions.cc
index ac185178..f438f739 100644
--- a/ssl/custom_extensions.c
+++ b/ssl/custom_extensions.cc
@@ -214,7 +214,8 @@ static int custom_ext_append(STACK_OF(SSL_CUSTOM_EXTENSION) **stack,
     return 0;
   }
 
-  SSL_CUSTOM_EXTENSION *ext = OPENSSL_malloc(sizeof(SSL_CUSTOM_EXTENSION));
+  SSL_CUSTOM_EXTENSION *ext =
+      (SSL_CUSTOM_EXTENSION *)OPENSSL_malloc(sizeof(SSL_CUSTOM_EXTENSION));
   if (ext == NULL) {
     return 0;
   }
diff --git a/ssl/d1_both.c b/ssl/d1_both.cc
similarity index 98%
rename from ssl/d1_both.c
rename to ssl/d1_both.cc
index 44e3f2ef..f25c2be8 100644
--- a/ssl/d1_both.c
+++ b/ssl/d1_both.cc
@@ -153,7 +153,7 @@ static void dtls1_hm_fragment_free(hm_fragment *frag) {
 }
 
 static hm_fragment *dtls1_hm_fragment_new(const struct hm_header_st *msg_hdr) {
-  hm_fragment *frag = OPENSSL_malloc(sizeof(hm_fragment));
+  hm_fragment *frag = (hm_fragment *)OPENSSL_malloc(sizeof(hm_fragment));
   if (frag == NULL) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
     return NULL;
@@ -164,7 +164,8 @@ static hm_fragment *dtls1_hm_fragment_new(const struct hm_header_st *msg_hdr) {
   frag->msg_len = msg_hdr->msg_len;
 
   /* Allocate space for the reassembled message and fill in the header. */
-  frag->data = OPENSSL_malloc(DTLS1_HM_HEADER_LENGTH + msg_hdr->msg_len);
+  frag->data =
+      (uint8_t *)OPENSSL_malloc(DTLS1_HM_HEADER_LENGTH + msg_hdr->msg_len);
   if (frag->data == NULL) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
     goto err;
@@ -191,7 +192,7 @@ static hm_fragment *dtls1_hm_fragment_new(const struct hm_header_st *msg_hdr) {
       goto err;
     }
     size_t bitmask_len = (msg_hdr->msg_len + 7) / 8;
-    frag->reassembly = OPENSSL_malloc(bitmask_len);
+    frag->reassembly = (uint8_t *)OPENSSL_malloc(bitmask_len);
     if (frag->reassembly == NULL) {
       OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
       goto err;
@@ -760,7 +761,7 @@ int dtls1_flush_flight(SSL *ssl) {
   dtls1_update_mtu(ssl);
 
   int ret = -1;
-  uint8_t *packet = OPENSSL_malloc(ssl->d1->mtu);
+  uint8_t *packet = (uint8_t *)OPENSSL_malloc(ssl->d1->mtu);
   if (packet == NULL) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
     goto err;
diff --git a/ssl/d1_lib.c b/ssl/d1_lib.cc
similarity index 99%
rename from ssl/d1_lib.c
rename to ssl/d1_lib.cc
index ef15252f..0074855b 100644
--- a/ssl/d1_lib.c
+++ b/ssl/d1_lib.cc
@@ -78,12 +78,10 @@
 #define DTLS1_MAX_TIMEOUTS                     12
 
 int dtls1_new(SSL *ssl) {
-  DTLS1_STATE *d1;
-
   if (!ssl3_new(ssl)) {
     return 0;
   }
-  d1 = OPENSSL_malloc(sizeof *d1);
+  DTLS1_STATE *d1 = (DTLS1_STATE *)OPENSSL_malloc(sizeof *d1);
   if (d1 == NULL) {
     ssl3_free(ssl);
     return 0;
diff --git a/ssl/d1_pkt.c b/ssl/d1_pkt.cc
similarity index 99%
rename from ssl/d1_pkt.c
rename to ssl/d1_pkt.cc
index e2c7315d..1ae55ebb 100644
--- a/ssl/d1_pkt.c
+++ b/ssl/d1_pkt.cc
@@ -171,7 +171,7 @@ again:
       /* Impossible in DTLS. */
       break;
 
-    case ssl_open_record_success:
+    case ssl_open_record_success: {
       if (CBS_len(&body) > 0xffff) {
         OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW);
         return -1;
@@ -182,6 +182,7 @@ again:
       rr->length = (uint16_t)CBS_len(&body);
       rr->data = (uint8_t *)CBS_data(&body);
       return 1;
+    }
 
     case ssl_open_record_discard:
       goto again;
diff --git a/ssl/d1_srtp.c b/ssl/d1_srtp.cc
similarity index 100%
rename from ssl/d1_srtp.c
rename to ssl/d1_srtp.cc
diff --git a/ssl/dtls_method.c b/ssl/dtls_method.cc
similarity index 100%
rename from ssl/dtls_method.c
rename to ssl/dtls_method.cc
diff --git a/ssl/dtls_record.c b/ssl/dtls_record.cc
similarity index 100%
rename from ssl/dtls_record.c
rename to ssl/dtls_record.cc
diff --git a/ssl/s3_both.c b/ssl/s3_both.cc
similarity index 99%
rename from ssl/s3_both.c
rename to ssl/s3_both.cc
index 65d438a1..5eb364d1 100644
--- a/ssl/s3_both.c
+++ b/ssl/s3_both.cc
@@ -131,7 +131,7 @@
 
 
 SSL_HANDSHAKE *ssl_handshake_new(SSL *ssl) {
-  SSL_HANDSHAKE *hs = OPENSSL_malloc(sizeof(SSL_HANDSHAKE));
+  SSL_HANDSHAKE *hs = (SSL_HANDSHAKE *)OPENSSL_malloc(sizeof(SSL_HANDSHAKE));
   if (hs == NULL) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
     return NULL;
diff --git a/ssl/s3_lib.c b/ssl/s3_lib.cc
similarity index 99%
rename from ssl/s3_lib.c
rename to ssl/s3_lib.cc
index ac8bb678..9548bbd4 100644
--- a/ssl/s3_lib.c
+++ b/ssl/s3_lib.cc
@@ -163,9 +163,7 @@
 
 
 int ssl3_new(SSL *ssl) {
-  SSL3_STATE *s3;
-
-  s3 = OPENSSL_malloc(sizeof *s3);
+  SSL3_STATE *s3 = (SSL3_STATE *)OPENSSL_malloc(sizeof *s3);
   if (s3 == NULL) {
     return 0;
   }
diff --git a/ssl/s3_pkt.c b/ssl/s3_pkt.cc
similarity index 99%
rename from ssl/s3_pkt.c
rename to ssl/s3_pkt.cc
index 445f8826..beaa08ed 100644
--- a/ssl/s3_pkt.c
+++ b/ssl/s3_pkt.cc
@@ -157,7 +157,7 @@ again:
       goto again;
     }
 
-    case ssl_open_record_success:
+    case ssl_open_record_success: {
       if (CBS_len(&body) > 0xffff) {
         OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW);
         return -1;
@@ -168,6 +168,7 @@ again:
       rr->length = (uint16_t)CBS_len(&body);
       rr->data = (uint8_t *)CBS_data(&body);
       return 1;
+    }
 
     case ssl_open_record_discard:
       goto again;
diff --git a/ssl/ssl_asn1.c b/ssl/ssl_asn1.cc
similarity index 98%
rename from ssl/ssl_asn1.c
rename to ssl/ssl_asn1.cc
index cc6a5596..1d6140e9 100644
--- a/ssl/ssl_asn1.c
+++ b/ssl/ssl_asn1.cc
@@ -80,6 +80,13 @@
  * OTHER ENTITY BASED ON INFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS OR
  * OTHERWISE. */
 
+/* Per C99, various stdint.h macros are unavailable in C++ unless some macros
+ * are defined. C++11 overruled this decision, but older Android NDKs still
+ * require it. */
+#if !defined(__STDC_LIMIT_MACROS)
+#define __STDC_LIMIT_MACROS
+#endif
+
 #include <openssl/ssl.h>
 
 #include <limits.h>
@@ -425,7 +432,7 @@ int SSL_SESSION_to_bytes(const SSL_SESSION *in, uint8_t **out_data,
     static const char kNotResumableSession[] = "NOT RESUMABLE";
 
     *out_len = strlen(kNotResumableSession);
-    *out_data = BUF_memdup(kNotResumableSession, *out_len);
+    *out_data = (uint8_t *)BUF_memdup(kNotResumableSession, *out_len);
     if (*out_data == NULL) {
       return 0;
     }
diff --git a/ssl/ssl_x509.c b/ssl/ssl_x509.cc
similarity index 99%
rename from ssl/ssl_x509.c
rename to ssl/ssl_x509.cc
index 65405aaf..77fc0e2a 100644
--- a/ssl/ssl_x509.c
+++ b/ssl/ssl_x509.cc
@@ -494,14 +494,13 @@ static void ssl_crypto_x509_cert_dup(CERT *new_cert, const CERT *cert) {
 }
 
 static int ssl_crypto_x509_session_cache_objects(SSL_SESSION *sess) {
-  STACK_OF(X509) *chain = NULL;
+  bssl::UniquePtr<STACK_OF(X509)> chain;
   const size_t num_certs = sk_CRYPTO_BUFFER_num(sess->certs);
-
   if (num_certs > 0) {
-    chain = sk_X509_new_null();
-    if (chain == NULL) {
+    chain.reset(sk_X509_new_null());
+    if (!chain) {
       OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
-      goto err;
+      return 0;
     }
   }
 
@@ -510,12 +509,12 @@ static int ssl_crypto_x509_session_cache_objects(SSL_SESSION *sess) {
     X509 *x509 = X509_parse_from_buffer(sk_CRYPTO_BUFFER_value(sess->certs, i));
     if (x509 == NULL) {
       OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
-      goto err;
+      return 0;
     }
-    if (!sk_X509_push(chain, x509)) {
+    if (!sk_X509_push(chain.get(), x509)) {
       OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
       X509_free(x509);
-      goto err;
+      return 0;
     }
     if (i == 0) {
       leaf = x509;
@@ -523,7 +522,7 @@ static int ssl_crypto_x509_session_cache_objects(SSL_SESSION *sess) {
   }
 
   sk_X509_pop_free(sess->x509_chain, X509_free);
-  sess->x509_chain = chain;
+  sess->x509_chain = chain.release();
   sk_X509_pop_free(sess->x509_chain_without_leaf, X509_free);
   sess->x509_chain_without_leaf = NULL;
 
@@ -532,12 +531,7 @@ static int ssl_crypto_x509_session_cache_objects(SSL_SESSION *sess) {
     X509_up_ref(leaf);
   }
   sess->x509_peer = leaf;
-
   return 1;
-
-err:
-  sk_X509_pop_free(chain, X509_free);
-  return 0;
 }
 
 static int ssl_crypto_x509_session_dup(SSL_SESSION *new_session,