diff --git a/src/components/views/rooms/ReadReceiptMarker.js b/src/components/views/rooms/ReadReceiptMarker.js
index 2fe577377d..1c490f019e 100644
--- a/src/components/views/rooms/ReadReceiptMarker.js
+++ b/src/components/views/rooms/ReadReceiptMarker.js
@@ -23,7 +23,7 @@ import { _t } from '../../../languageHandler';
 import {formatDate} from '../../../DateUtils';
 import Velociraptor from "../../../Velociraptor";
 import * as sdk from "../../../index";
-import {toRem} from "../../../utils/units";
+import {toPx} from "../../../utils/units";
 
 let bounce = false;
 try {
@@ -149,7 +149,7 @@ export default createReactClass({
             // start at the old height and in the old h pos
 
             startStyles.push({ top: startTopOffset+"px",
-                               left: toRem(oldInfo.left) });
+                               left: toPx(oldInfo.left) });
 
             const reorderTransitionOpts = {
                 duration: 100,
@@ -182,7 +182,7 @@ export default createReactClass({
         }
 
         const style = {
-            left: toRem(this.props.leftOffset),
+            left: toPx(this.props.leftOffset),
             top: '0px',
             visibility: this.props.hidden ? 'hidden' : 'visible',
         };