diff --git a/src/includes/constants.php b/src/includes/constants.php
index 2cffccb7d..17b67166a 100644
--- a/src/includes/constants.php
+++ b/src/includes/constants.php
@@ -58,9 +58,10 @@ if (!defined('BASE_PATH')) {
             }
         }
 
-        // Determine BASE_PATH by assuming that this file is framework/src/Core/Constants.php
-        //  we can then determine the base path
-        $candidateBasePath = rtrim(dirname(dirname(dirname(__DIR__))), DIRECTORY_SEPARATOR);
+        // Determine BASE_PATH by assuming that this file is vendor/silverstripe/framework/src/includes/constants.php
+        // we can then determine the base path
+        $candidateBasePath = rtrim(dirname(__DIR__, 5), DIRECTORY_SEPARATOR);
+
         // We can't have an empty BASE_PATH.  Making it / means that double-slashes occur in places but that's benign.
         // This likely only happens on chrooted environemnts
         return $candidateBasePath ?: DIRECTORY_SEPARATOR;