diff --git a/src/opnsense/mvc/app/config/services.php b/src/opnsense/mvc/app/config/services.php
index fa36a6d7c..8dd6dd57b 100644
--- a/src/opnsense/mvc/app/config/services.php
+++ b/src/opnsense/mvc/app/config/services.php
@@ -52,7 +52,7 @@ $di->set('view', function () use ($config) {
             ));
             // register additional volt template functions
             $volt->getCompiler()->addFunction('theme_file_or_default', 'view_fetch_themed_filename');
-            $volt->getCompiler()->addFunction('file_exists', 'file_exists');
+            $volt->getCompiler()->addFunction('file_exists', 'view_file_exists');
 
             return $volt;
         },
diff --git a/src/opnsense/www/index.php b/src/opnsense/www/index.php
index eac29f57e..8fe865126 100644
--- a/src/opnsense/www/index.php
+++ b/src/opnsense/www/index.php
@@ -23,6 +23,16 @@ function view_fetch_themed_filename($url, $theme)
     return $url; // not found, return source
 }
 
+/**
+ * check if file exists, wrapper around file_exists() so services.php can define other implementation for local testing
+ * @param string $filename to check
+ * @return boolean
+ */
+function view_file_exists($filename)
+{
+    return file_exists($filename);
+}
+
 try {
     /**
      * Read the configuration