diff --git a/src/http/ngx_http_variables.c b/src/http/ngx_http_variables.c
index d6bb92c..78cfa23 100644
--- a/src/http/ngx_http_variables.c
+++ b/src/http/ngx_http_variables.c
@@ -432,7 +432,7 @@
 
     v = &r->variables[index];
 
-    if (v->valid) {
+    if (v->valid || v->not_found) {
         if (!v->no_cacheable) {
             return v;
         }