diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index d437ba0..5da4f11 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -3675,10 +3675,13 @@
 //#define MBEDTLS_SSL_CONF_RECV_TIMEOUT mbedtls_net_recv_timeout
 
 /* The PRNG to use by the SSL module. If defined, this must
- * evaluate to the name on externally defined function with signature
+ * evaluate to the name of an externally defined function with signature
  * int f_rng(void *, unsigned char *, size_t),
  * which ignores its first parameter (the stack will always
  * pass NULL to this function).
+ * NB: The reason not to drop the context parameter entirely
+ * is for compatibility with the Crypto and X.509 libraries
+ * which use RNG callbacks including context parameters.
  */
 //#define MBEDTLS_SSL_CONF_RNG rng_wrap
 
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 1f09977..b6a3b60 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -939,7 +939,9 @@
 #if !defined(MBEDTLS_SSL_CONF_SINGLE_CIPHERSUITE)
     int ciphersuite;            /*!< chosen ciphersuite */
 #endif /* MBEDTLS_SSL_CONF_SINGLE_CIPHERSUITE */
+#if defined(MBEDTLS_ZLIB_SUPPORT)
     int compression;            /*!< chosen compression */
+#endif /* MBEDTLS_ZLIB_SUPPORT */
     size_t id_len;              /*!< session id length  */
     unsigned char id[32];       /*!< session identifier */
     unsigned char master[48];   /*!< the master secret  */
diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index 563801f..f8f4090 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -1828,6 +1828,21 @@
     ssl->pending_fatal_alert_msg = message;
 }
 
+/*
+ * Getter functions for fields in SSL session.
+ */
+
+static inline int mbedtls_ssl_session_get_compression(
+    mbedtls_ssl_session const *session )
+{
+#if defined(MBEDTLS_ZLIB_SUPPORT)
+    return( session->compression );
+#else
+    ( (void) session );
+    return( MBEDTLS_SSL_COMPRESS_NULL );
+#endif
+}
+
 #define MBEDTLS_SSL_CHK(f) do { if( ( ret = f ) < 0 ) goto cleanup; } while( 0 )
 
 #if defined(MBEDTLS_USE_TINYCRYPT)
diff --git a/library/ssl_cache.c b/library/ssl_cache.c
index bcc2f59..90e2a81 100644
--- a/library/ssl_cache.c
+++ b/library/ssl_cache.c
@@ -86,7 +86,8 @@
 
         if( mbedtls_ssl_session_get_ciphersuite( session ) !=
             mbedtls_ssl_session_get_ciphersuite( &entry->session ) ||
-            session->compression != entry->session.compression ||
+            mbedtls_ssl_session_get_compression( session ) !=
+            mbedtls_ssl_session_get_compression( &entry->session ) ||
             session->id_len != entry->session.id_len )
         {
             continue;
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index be83f53..8903431 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -1843,7 +1843,7 @@
     if( n == 0 ||
         mbedtls_ssl_get_renego_status( ssl ) != MBEDTLS_SSL_INITIAL_HANDSHAKE ||
         mbedtls_ssl_session_get_ciphersuite( ssl->session_negotiate ) != i ||
-        ssl->session_negotiate->compression != comp ||
+        mbedtls_ssl_session_get_compression( ssl->session_negotiate ) != comp ||
         ssl->session_negotiate->id_len != n ||
         memcmp( ssl->session_negotiate->id, buf + 35, n ) != 0 )
     {
@@ -1874,7 +1874,9 @@
 #if !defined(MBEDTLS_SSL_CONF_SINGLE_CIPHERSUITE)
         ssl->session_negotiate->ciphersuite = i;
 #endif /* MBEDTLS_SSL_CONF_SINGLE_CIPHERSUITE */
+#if defined(MBEDTLS_ZLIB_SUPPORT)
         ssl->session_negotiate->compression = comp;
+#endif
         ssl->session_negotiate->id_len = n;
         memcpy( ssl->session_negotiate->id, buf + 35, n );
     }
@@ -1938,7 +1940,9 @@
                                       MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
         return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
     }
+#if defined(MBEDTLS_ZLIB_SUPPORT)
     ssl->session_negotiate->compression = comp;
+#endif
 
     ext = buf + 40 + n;
 
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 559c881..c25482d 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -1810,8 +1810,8 @@
     MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, compression",
                       buf + comp_offset + 1, comp_len );
 
-    ssl->session_negotiate->compression = MBEDTLS_SSL_COMPRESS_NULL;
 #if defined(MBEDTLS_ZLIB_SUPPORT)
+    ssl->session_negotiate->compression = MBEDTLS_SSL_COMPRESS_NULL;
     for( i = 0; i < comp_len; ++i )
     {
         if( buf[comp_offset + 1 + i] == MBEDTLS_SSL_COMPRESS_DEFLATE )
@@ -1820,13 +1820,13 @@
             break;
         }
     }
-#endif
 
     /* See comments in ssl_write_client_hello() */
 #if defined(MBEDTLS_SSL_PROTO_DTLS)
     if( MBEDTLS_SSL_TRANSPORT_IS_DTLS( ssl->conf->transport ) )
         ssl->session_negotiate->compression = MBEDTLS_SSL_COMPRESS_NULL;
 #endif
+#endif /* MBEDTLS_ZLIB_SUPPORT */
 
     /* Do not parse the extensions if the protocol is SSLv3 */
 #if defined(MBEDTLS_SSL_PROTO_SSL3)
@@ -2893,12 +2893,13 @@
     ciphersuite = mbedtls_ssl_session_get_ciphersuite( ssl->session_negotiate );
     *p++ = (unsigned char)( ciphersuite >> 8 );
     *p++ = (unsigned char)( ciphersuite      );
-    *p++ = (unsigned char)( ssl->session_negotiate->compression      );
+    *p++ = (unsigned char)(
+        mbedtls_ssl_session_get_compression( ssl->session_negotiate ) );
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, chosen ciphersuite: %s",
            mbedtls_ssl_get_ciphersuite_name( ciphersuite ) ) );
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, compress alg.: 0x%02X",
-                   ssl->session_negotiate->compression ) );
+              mbedtls_ssl_session_get_compression( ssl->session_negotiate ) ) );
 
     /* Do not write the extensions if the protocol is SSLv3 */
 #if defined(MBEDTLS_SSL_PROTO_SSL3)
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 3cceb66..a6492f4 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -9645,6 +9645,12 @@
 #define SSL_SERIALIZED_SESSION_CONFIG_KEEP_CRT 0
 #endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
 
+#if defined(MBEDTLS_ZLIB_SUPPORT)
+#define SSL_SERIALIZED_SESSION_CONFIG_COMPRESSION 1
+#else
+#define SSL_SERIALIZED_SESSION_CONFIG_COMPRESSION 0
+#endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+
 #define SSL_SERIALIZED_SESSION_CONFIG_TIME_BIT          0
 #define SSL_SERIALIZED_SESSION_CONFIG_CRT_BIT           1
 #define SSL_SERIALIZED_SESSION_CONFIG_CLIENT_TICKET_BIT 2
@@ -9653,6 +9659,7 @@
 #define SSL_SERIALIZED_SESSION_CONFIG_ETM_BIT           5
 #define SSL_SERIALIZED_SESSION_CONFIG_TICKET_BIT        6
 #define SSL_SERIALIZED_SESSION_CONFIG_KEEP_CRT_BIT      7
+#define SSL_SERIALIZED_SESSION_CONFIG_COMPRESSION_BIT   8
 
 #define SSL_SERIALIZED_SESSION_CONFIG_BITFLAG                           \
     ( (uint16_t) (                                                      \
@@ -9663,6 +9670,7 @@
         ( SSL_SERIALIZED_SESSION_CONFIG_TRUNC_HMAC    << SSL_SERIALIZED_SESSION_CONFIG_TRUNC_HMAC_BIT    ) | \
         ( SSL_SERIALIZED_SESSION_CONFIG_ETM           << SSL_SERIALIZED_SESSION_CONFIG_ETM_BIT           ) | \
         ( SSL_SERIALIZED_SESSION_CONFIG_TICKET        << SSL_SERIALIZED_SESSION_CONFIG_TICKET_BIT        ) | \
+        ( SSL_SERIALIZED_SESSION_CONFIG_COMPRESSION   << SSL_SERIALIZED_SESSION_CONFIG_COMPRESSION_BIT   ) | \
         ( SSL_SERIALIZED_SESSION_CONFIG_KEEP_CRT      << SSL_SERIALIZED_SESSION_CONFIG_KEEP_CRT_BIT      ) ) )
 
 static unsigned char ssl_serialized_session_header[] = {
@@ -9768,12 +9776,28 @@
     /*
      * Basic mandatory fields
      */
-    used += 2   /* ciphersuite */
-          + 1   /* compression */
-          + 1   /* id_len */
-          + sizeof( session->id )
-          + sizeof( session->master )
-          + 4;  /* verify_result */
+    {
+        size_t const ciphersuite_len = 2;
+#if defined(MBEDTLS_ZLIB_SUPPORT)
+        size_t const compression_len = 1;
+#else
+        size_t const compression_len = 0;
+#endif
+        size_t const id_len_len = 1;
+        size_t const id_len = 32;
+        size_t const master_len = 48;
+        size_t const verif_result_len = 4;
+
+        size_t const basic_len =
+            ciphersuite_len +
+            compression_len +
+            id_len_len      +
+            id_len          +
+            master_len      +
+            verif_result_len;
+
+        used += basic_len;
+    }
 
     if( used <= buf_len )
     {
@@ -9782,7 +9806,10 @@
         *p++ = (unsigned char)( ( ciphersuite >> 8 ) & 0xFF );
         *p++ = (unsigned char)( ( ciphersuite      ) & 0xFF );
 
-        *p++ = (unsigned char)( session->compression & 0xFF );
+#if defined(MBEDTLS_ZLIB_SUPPORT)
+        *p++ = (unsigned char)(
+            mbedtls_ssl_session_get_compression( session ) );
+#endif
 
         *p++ = (unsigned char)( session->id_len & 0xFF );
         memcpy( p, session->id, 32 );
@@ -9980,9 +10007,29 @@
     /*
      * Basic mandatory fields
      */
+    {
+        size_t const ciphersuite_len = 2;
+#if defined(MBEDTLS_ZLIB_SUPPORT)
+        size_t const compression_len = 1;
+#else
+        size_t const compression_len = 0;
+#endif
+        size_t const id_len_len = 1;
+        size_t const id_len = 32;
+        size_t const master_len = 48;
+        size_t const verif_result_len = 4;
 
-    if( 2 + 1 + 1 + 32 + 48 + 4 > (size_t)( end - p ) )
-        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+        size_t const basic_len =
+            ciphersuite_len +
+            compression_len +
+            id_len_len      +
+            id_len          +
+            master_len      +
+            verif_result_len;
+
+        if( basic_len > (size_t)( end - p ) )
+            return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
 
     ciphersuite = ( p[0] << 8 ) | p[1];
     p += 2;
@@ -9997,7 +10044,9 @@
     }
 #endif
 
+#if defined(MBEDTLS_ZLIB_SUPPORT)
     session->compression = *p++;
+#endif
 
     session->id_len = *p++;
     memcpy( session->id, p, 32 );
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index 7d7845e..2c4a6b4 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -286,7 +286,9 @@
 #if !defined(MBEDTLS_SSL_CONF_SINGLE_CIPHERSUITE)
     session->ciphersuite = 0xabcd;
 #endif
+#if defined(MBEDTLS_ZLIB_SUPPORT)
     session->compression = 1;
+#endif
     session->id_len = sizeof( session->id );
     memset( session->id, 66, session->id_len );
     memset( session->master, 17, sizeof( session->master ) );
@@ -716,7 +718,9 @@
 #if !defined(MBEDTLS_SSL_CONF_SINGLE_CIPHERSUITE)
     TEST_ASSERT( original.ciphersuite == restored.ciphersuite );
 #endif
+#if defined(MBEDTLS_ZLIB_SUPPORT)
     TEST_ASSERT( original.compression == restored.compression );
+#endif
     TEST_ASSERT( original.id_len == restored.id_len );
     TEST_ASSERT( memcmp( original.id,
                          restored.id, sizeof( original.id ) ) == 0 );