diff --git a/common/content/buffer.js b/common/content/buffer.js
index 033d8b1b..0bd9e7e2 100644
--- a/common/content/buffer.js
+++ b/common/content/buffer.js
@@ -1225,10 +1225,11 @@ var Buffer = Module("buffer", {
         else
             throw Error();
 
+        dactyl.assert(number < 0 ? elem.scrollLeft > 0 : elem.scrollLeft < elem.scrollWidth - elem.clientWidth);
+
         let left = elem.dactylScrollDestX !== undefined ? elem.dactylScrollDestX : elem.scrollLeft;
         elem.dactylScrollDestX = undefined;
 
-        dactyl.assert(number < 0 ? left > 0 : left < elem.scrollWidth - elem.clientWidth);
         Buffer.scrollTo(elem, left + number * increment, null);
     },
 
@@ -1253,10 +1254,11 @@ var Buffer = Module("buffer", {
         else
             throw Error();
 
+        dactyl.assert(number < 0 ? elem.scrollTop > 0 : elem.scrollTop < elem.scrollHeight - elem.clientHeight);
+
         let top = elem.dactylScrollDestY !== undefined ? elem.dactylScrollDestY : elem.scrollTop;
         elem.dactylScrollDestY = undefined;
 
-        dactyl.assert(number < 0 ? top > 0 : top < elem.scrollHeight - elem.clientHeight);
         Buffer.scrollTo(elem, null, top + number * increment);
     },
 
diff --git a/common/content/disable-acr.jsm b/common/content/disable-acr.jsm
index 7379d26f..3481cda8 100644
--- a/common/content/disable-acr.jsm
+++ b/common/content/disable-acr.jsm
@@ -57,7 +57,7 @@ function checkDocument(doc, disable, force) {
 }
 
 function chromeDocuments() {
-    let windows = services.windowMediator.getXULWindowEnumerator(null);
+    let windows = Services.wm.getXULWindowEnumerator(null);
     while (windows.hasMoreElements()) {
         let window = windows.getNext().QueryInterface(Ci.nsIXULWindow);
         for each (let type in ["typeChrome", "typeContent"]) {
diff --git a/common/content/mappings.js b/common/content/mappings.js
index ea539199..ed4104d6 100644
--- a/common/content/mappings.js
+++ b/common/content/mappings.js
@@ -477,7 +477,8 @@ var Mappings = Module("mappings", {
                     return;
                 }
 
-                if (args[1] && !args["-count"] && !args["-ex"] && !args["-javascript"])
+                if (args[1] && !/^<nop>$/i.test(args[1])
+                    && !args["-count"] && !args["-ex"] && !args["-javascript"])
                     args[1] = "<count>" + args[1];
 
                 let [lhs, rhs] = args;