diff --git a/src/elements/dygraphchart.js b/src/elements/dygraphchart.js
index accdb9f..8b0ad05 100644
--- a/src/elements/dygraphchart.js
+++ b/src/elements/dygraphchart.js
@@ -11,6 +11,7 @@ export class Dygraphchart {
   @bindable refindex;
   @bindable refvalues=1;
   @bindable throttle=200; //time to throttle chart update, if it is too much at once
+  @bindable convertors;
   initialdata = true;
   refindices = null;
   xy = false;
diff --git a/src/elements/sachart.js b/src/elements/sachart.js
index e1d2fba..ac158b2 100644
--- a/src/elements/sachart.js
+++ b/src/elements/sachart.js
@@ -11,6 +11,7 @@ export class Sachart extends Dygraphchart {
     @bindable pH=7.4;
     @bindable pCO2=40;
     @bindable throttle=2000; //time to throttle chart update, if it is too much at once
+    @bindable convertors;
 
     constructor(){
         super();