diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 1d5503b9b..a773c9d92 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -1960,7 +1960,7 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
 
     /* Allocate compression buffer */
 #if defined(MBEDTLS_ZLIB_SUPPORT)
-    if( session->compression == MBEDTLS_SSL_COMPRESS_DEFLATE &&
+    if( ssl->session_negotiate->compression == MBEDTLS_SSL_COMPRESS_DEFLATE &&
         ssl->compress_buf == NULL )
     {
         MBEDTLS_SSL_DEBUG_MSG( 3, ( "Allocating compression buffer" ) );