diff --git a/src/http/ngx_http_request.c b/src/http/ngx_http_request.c
index 2e7c30f..2d1845d 100644
--- a/src/http/ngx_http_request.c
+++ b/src/http/ngx_http_request.c
@@ -2176,15 +2176,16 @@
             }
             break;
 
-        case '\0':
-            return NGX_DECLINED;
-
         default:
 
             if (ngx_path_separator(ch)) {
                 return NGX_DECLINED;
             }
 
+            if (ch <= 0x20 || ch == 0x7f) {
+                return NGX_DECLINED;
+            }
+
             if (ch >= 'A' && ch <= 'Z') {
                 alloc = 1;
             }