diff --git a/service.js b/service.js
index 1dd7a0e..fbda36e 100644
--- a/service.js
+++ b/service.js
@@ -496,7 +496,7 @@ class BesService {
                 y1,
                 y2,
                 scale,
-                replacement.substr(lengthDiff).trim()
+                replacement.slice(0, lengthDiff).trim()
               )
             }
           } else if (replacement.substr(0, context.length) === context) {