diff --git a/tests/http/testenv/mod_curltest/mod_curltest.c b/tests/http/testenv/mod_curltest/mod_curltest.c
index 25f32c7904..3eec35381d 100644
--- a/tests/http/testenv/mod_curltest/mod_curltest.c
+++ b/tests/http/testenv/mod_curltest/mod_curltest.c
@@ -404,7 +404,10 @@ static int curltest_tweak_handler(request_rec *r)
   ap_log_rerror(APLOG_MARK, APLOG_TRACE1, 0, r, "error_handler: processing "
                 "request, %s", r->args? r->args : "(no args)");
   r->status = http_status;
-  r->clength = with_cl ? (chunks * chunk_size) : -1;
+  if(with_cl)
+    r->clength = (apr_off_t)chunks * chunk_size;
+  else
+    r->clength = -1;
   r->chunked = (r->proto_num >= HTTP_VERSION(1, 1)) && !with_cl;
   apr_table_setn(r->headers_out, "request-id", request_id);
   if(r->clength >= 0) {