diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 8d49be4..f81a5e2 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -2180,6 +2180,12 @@
 
     if( ssl->in_hslen != 0 )
     {
+        if( ssl->in_offt != NULL )
+        {
+            SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+            return( POLARSSL_ERR_SSL_INTERNAL_ERROR );
+        }
+
         /*
          * Get next Handshake message in the current record
          */