diff --git a/common/content/buffer.js b/common/content/buffer.js
index b8f6af15..48e43082 100644
--- a/common/content/buffer.js
+++ b/common/content/buffer.js
@@ -1146,7 +1146,8 @@ var Buffer = Module("buffer", {
             throw Error();
 
         let left = "dactylScrollDestX" in elem ? elem.dactylScrollDestX : elem.scrollLeft;
-        delete elem.dactylScrollDestX;
+        if ("dactylScrollDestX" in elem)
+            delete elem.dactylScrollDestX;
 
         dactyl.assert(number < 0 ? left > 0 : left < elem.scrollWidth - elem.clientWidth);
         Buffer.scrollTo(elem, left + number * increment, null);
@@ -1162,7 +1163,8 @@ var Buffer = Module("buffer", {
             throw Error();
 
         let top = "dactylScrollDestY" in elem ? elem.dactylScrollDestY : elem.scrollTop;
-        delete elem.dactylScrollDestY;
+        if ("dactylScrollDestY" in elem)
+            delete elem.dactylScrollDestY;
 
         dactyl.assert(number < 0 ? top > 0 : top < elem.scrollHeight - elem.clientHeight);
         Buffer.scrollTo(elem, null, top + number * increment);