diff --git a/src/core/ngx_inet.c b/src/core/ngx_inet.c
index de4cae2..31094ba 100644
--- a/src/core/ngx_inet.c
+++ b/src/core/ngx_inet.c
@@ -214,7 +214,13 @@
 
     in_cidr->mask = htonl((ngx_uint_t) (0 - (1 << (32 - m))));
 
-    return NGX_OK;
+    if (in_cidr->addr == (in_cidr->addr & in_cidr->mask)) {
+        return NGX_OK;
+    }
+
+    in_cidr->addr &= in_cidr->mask;
+
+    return NGX_DONE;
 }