diff --git a/src/core/ngx_conf_file.c b/src/core/ngx_conf_file.c
index 1f6b1f732..c58d8095f 100644
--- a/src/core/ngx_conf_file.c
+++ b/src/core/ngx_conf_file.c
@@ -12,6 +12,7 @@
 static ngx_int_t ngx_conf_handler(ngx_conf_t *cf, ngx_int_t last);
 static ngx_int_t ngx_conf_read_token(ngx_conf_t *cf);
 static char *ngx_conf_include(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
+static ngx_int_t ngx_conf_test_full_name(ngx_str_t *name);
 static void ngx_conf_flush_files(ngx_cycle_t *cycle);
 
 
@@ -802,29 +803,15 @@ ngx_int_t
 ngx_conf_full_name(ngx_cycle_t *cycle, ngx_str_t *name, ngx_uint_t conf_prefix)
 {
     size_t      len;
-    u_char     *p, *prefix;
-    ngx_str_t   old;
+    u_char     *p, *n, *prefix;
+    ngx_int_t   rc;
 
-#if (NGX_WIN32)
+    rc = ngx_conf_test_full_name(name);
 
-    if (name->len > 2
-        && name->data[1] == ':'
-        && ((name->data[0] >= 'a' && name->data[0] <= 'z')
-             || (name->data[0] >= 'A' && name->data[0] <= 'Z')))
-    {
-        return NGX_OK;
+    if (rc == NGX_OK) {
+        return rc;
     }
 
-#else
-
-    if (name->data[0] == '/') {
-        return NGX_OK;
-    }
-
-#endif
-
-    old = *name;
-
     if (conf_prefix) {
         len = cycle->conf_prefix.len;
         prefix = cycle->conf_prefix.data;
@@ -834,19 +821,79 @@ ngx_conf_full_name(ngx_cycle_t *cycle, ngx_str_t *name, ngx_uint_t conf_prefix)
         prefix = cycle->prefix.data;
     }
 
-    name->len = len + old.len;
-    name->data = ngx_pnalloc(cycle->pool, name->len + 1);
-    if (name->data == NULL) {
+#if (NGX_WIN32)
+
+    if (rc == 2) {
+        len = rc;
+    }
+
+#endif
+
+    n = ngx_pnalloc(cycle->pool, len + name->len + 1);
+    if (n == NULL) {
         return NGX_ERROR;
     }
 
-    p = ngx_cpymem(name->data, prefix, len);
-    ngx_cpystrn(p, old.data, old.len + 1);
+    p = ngx_cpymem(n, prefix, len);
+    ngx_cpystrn(p, name->data, name->len + 1);
+
+    name->len += len;
+    name->data = n;
 
     return NGX_OK;
 }
 
 
+static ngx_int_t
+ngx_conf_test_full_name(ngx_str_t *name)
+{
+#if (NGX_WIN32)
+    u_char  c0, c1;
+
+    c0 = name->data[0];
+
+    if (name->len < 2) {
+        if (c0 == '/') {
+            return 2;
+        }
+
+        return NGX_DECLINED;
+    }
+
+    c1 = name->data[1];
+
+    if (c1 == ':') {
+        c0 |= 0x20;
+
+        if ((c0 >= 'a' && c0 <= 'z')) {
+            return NGX_OK;
+        }
+
+        return NGX_DECLINED;
+    }
+
+    if (c1 == '/') {
+        return NGX_OK;
+    }
+
+    if (c0 == '/') {
+        return 2;
+    }
+
+    return NGX_DECLINED;
+
+#else
+
+    if (name->data[0] == '/') {
+        return NGX_OK;
+    }
+
+    return NGX_DECLINED;
+
+#endif
+}
+
+
 ngx_open_file_t *
 ngx_conf_open_file(ngx_cycle_t *cycle, ngx_str_t *name)
 {