diff --git a/src/modules/tm/t_msgbuilder.c b/src/modules/tm/t_msgbuilder.c
index ef9b45e2461..27aaef9b5fa 100644
--- a/src/modules/tm/t_msgbuilder.c
+++ b/src/modules/tm/t_msgbuilder.c
@@ -1637,7 +1637,7 @@ char* build_uac_req(str* method, str* headers, str* body, dlg_t* dialog,
 			memapp(w, CRLF, CRLF_LEN);
 	}
 	memapp(w, CRLF, CRLF_LEN);
-	if (body) memapp(w, body->s, body->len);
+	if (body && body->s && body->len>0) memapp(w, body->s, body->len);
 
 #ifdef EXTRA_DEBUG
 	assert(w-buf == *len);