diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 013e223..2175523 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -527,11 +527,13 @@
 
 static int ssl_write_server_key_exchange( ssl_context *ssl )
 {
+#if defined(POLARSSL_DHM_C)
     int ret;
     size_t n, rsa_key_len = 0;
     unsigned char hash[36];
     md5_context md5;
     sha1_context sha1;
+#endif
 
     SSL_DEBUG_MSG( 2, ( "=> write server key exchange" ) );