diff --git a/trailing_slash.module b/trailing_slash.module
index 38dd83d..47629b9 100644
--- a/trailing_slash.module
+++ b/trailing_slash.module
@@ -38,7 +38,15 @@ function trailing_slash_url_outbound_alter(&$path, &$options, $original_path) {
   if (module_exists('globalredirect') && ($settings = _globalredirect_get_settings()) && _globalredirect_is_active($settings) && !$settings['deslash']) {
     // Use backtrace to find out if the globalredirect_init() function called
     // this function.
-    $backtrace = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 3);
+    if (version_compare(PHP_VERSION, '5.4') >= 0) {
+      $backtrace = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 3);
+    }
+    elseif (version_compare(PHP_VERSION, '5.3.6') >= 0) {
+      $backtrace = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS);
+    }
+    else {
+      $backtrace = debug_backtrace(FALSE);
+    }
     if (isset($backtrace[2]) && isset($backtrace[2]['function']) && strtolower($backtrace[2]['function']) == 'globalredirect_init') {
       return;
     }