ngx_strlow()

diff --git a/src/http/modules/ngx_http_fastcgi_module.c b/src/http/modules/ngx_http_fastcgi_module.c
index b975c06..e310bbb 100644
--- a/src/http/modules/ngx_http_fastcgi_module.c
+++ b/src/http/modules/ngx_http_fastcgi_module.c

@@ -1120,9 +1120,7 @@
                     ngx_memcpy(h->lowcase_key, r->lowcase_header, h->key.len);
 
                 } else {
-                    for (i = 0; i < h->key.len; i++) {
-                        h->lowcase_key[i] = ngx_tolower(h->key.data[i]);
-                    }
+                    ngx_strlow(h->lowcase_key, h->key.data, h->key.len);
                 }
 
                 hh = ngx_hash_find(&umcf->headers_in_hash, h->hash,

diff --git a/src/http/modules/ngx_http_proxy_module.c b/src/http/modules/ngx_http_proxy_module.c
index 8a7f2ab..880d998 100644
--- a/src/http/modules/ngx_http_proxy_module.c
+++ b/src/http/modules/ngx_http_proxy_module.c

@@ -1196,7 +1196,6 @@
 ngx_http_proxy_process_header(ngx_http_request_t *r)
 {
     ngx_int_t                       rc;
-    ngx_uint_t                      i;
     ngx_table_elt_t                *h;
     ngx_http_upstream_header_t     *hh;
     ngx_http_upstream_main_conf_t  *umcf;
@@ -1237,9 +1236,7 @@
                 ngx_memcpy(h->lowcase_key, r->lowcase_header, h->key.len);
 
             } else {
-                for (i = 0; i < h->key.len; i++) {
-                    h->lowcase_key[i] = ngx_tolower(h->key.data[i]);
-                }
+                ngx_strlow(h->lowcase_key, h->key.data, h->key.len);
             }
 
             hh = ngx_hash_find(&umcf->headers_in_hash, h->hash,

diff --git a/src/http/modules/ngx_http_sub_filter_module.c b/src/http/modules/ngx_http_sub_filter_module.c
index e45ca6e..62a8f08 100644
--- a/src/http/modules/ngx_http_sub_filter_module.c
+++ b/src/http/modules/ngx_http_sub_filter_module.c

@@ -632,7 +632,6 @@
 
     ngx_str_t                  *value;
     ngx_int_t                   n;
-    ngx_uint_t                  i;
     ngx_http_script_compile_t   sc;
 
     if (slcf->match.len) {
@@ -641,11 +640,9 @@
 
     value = cf->args->elts;
 
-    slcf->match = value[1];
+    ngx_strlow(value[1].data, value[1].data, value[1].len);
 
-    for (i = 0; i < value[1].len; i++) {
-        value[1].data[i] = ngx_tolower(value[1].data[i]);
-    }
+    slcf->match = value[1];
 
     n = ngx_http_script_variables_count(&value[2]);