diff --git a/test/test.js b/test/test.js
index 38659f875d8d0635fcc3d75d58614c95a129b5ff..c4941cfe3d667da4a6cfb3be35b0bac513d15f67 100644
--- a/test/test.js
+++ b/test/test.js
@@ -2216,6 +2216,8 @@ function makeItWrapAfter(cm, pos) {
     cm.setSize(w);
     posTop = cm.charCoords(pos).top;
   }
+  // Firefox > 50 compresses a space when two spaces from different bidi spans meet
+  cm.setSize(w + 10);
 }
 
 function testMoveBidi(str) {