diff --git a/contrib/calcDistance.lua b/contrib/calcDistance.lua
index 34330c9..453b832 100644
--- a/contrib/calcDistance.lua
+++ b/contrib/calcDistance.lua
@@ -25,7 +25,7 @@ USAGE
 * register a shortcut
 ]]
    
-dt = require "darktable"
+local dt = require "darktable"
 dt.configuration.check_version(...,{2,0,1})
 
 function isnan(x) return x ~= x end