diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index c584370..11d66ee 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -642,6 +642,12 @@
     z_stream ctx_deflate;               /*!<  compression context     */
     z_stream ctx_inflate;               /*!<  decompression context   */
 #endif
+
+#if defined(MBEDTLS_SSL_CONTEXT_SERIALIZATION)
+    /* We need the Hello random bytes in order to re-derive keys from the
+     * Master Secret and other session info, see ssl_populate_transform() */
+    unsigned char randbytes[64]; /*!< ServerHello.random+ClientHello.random */
+#endif /* MBEDTLS_SSL_CONTEXT_SERIALIZATION */
 };
 
 /*
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index a978899..0720147 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -1046,13 +1046,19 @@
     (void) ssl;
 #endif
 
-    /* Copy info about negotiated version and extensions */
+    /*
+     * Some data just needs copying into the structure
+     */
 #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC) && \
     defined(MBEDTLS_SSL_SOME_MODES_USE_MAC)
     transform->encrypt_then_mac = encrypt_then_mac;
 #endif
     transform->minor_ver = minor_ver;
 
+#if defined(MBEDTLS_SSL_CONTEXT_SERIALIZATION)
+    memcpy( transform->randbytes, randbytes, sizeof( transform->randbytes ) );
+#endif
+
     /*
      * Get various info structures
      */