diff --git a/src/core_plugins/timelion/public/panels/timechart/schema.js b/src/core_plugins/timelion/public/panels/timechart/schema.js
index d5f1c19ced270..c80595082bafa 100644
--- a/src/core_plugins/timelion/public/panels/timechart/schema.js
+++ b/src/core_plugins/timelion/public/panels/timechart/schema.js
@@ -217,6 +217,7 @@ module.exports = function timechartFn(Private, config, $rootScope, timefilter, $
                 // This is kind of gross, it means that you can't replace a global value with a null
                 // best you can do is an empty string. Deal with it.
                 if (objVal == null) return srcVal;
+                if (srcVal == null) return objVal;
               });
             }