diff --git a/hterm/js/hterm_screen.js b/hterm/js/hterm_screen.js
index 4d4bb0eb..a1b3b410 100644
--- a/hterm/js/hterm_screen.js
+++ b/hterm/js/hterm_screen.js
@@ -927,6 +927,10 @@ hterm.Screen.prototype.expandSelectionWithWordBreakMatches_ =
     return;
   }
 
+  if (selection.rangeCount == 0) {
+    return;
+  }
+
   const range = selection.getRangeAt(0);
   if (!range || range.toString().match(/\s/)) {
     return;