diff --git a/common/content/events.js b/common/content/events.js
index ff6aaebf..a1393e60 100644
--- a/common/content/events.js
+++ b/common/content/events.js
@@ -916,7 +916,7 @@ var Events = Module("events", {
         let start = Date.now();
         let end = start + (maxWaitTime * 1000);
 
-        util.waitFor(function () !events.feedingKeys || buffer.loaded || Date.now() > end);
+        util.waitFor(function () !events.feedingKeys || buffer.loaded, this, maxWaitTime);
         commandline.clear();
 
         if (!buffer.loaded)
diff --git a/common/modules/completion.jsm b/common/modules/completion.jsm
index 9f291f02..afd866ac 100644
--- a/common/modules/completion.jsm
+++ b/common/modules/completion.jsm
@@ -804,9 +804,7 @@ var CompletionContext = Class("CompletionContext", {
      *    If 0 or null, wait indefinitely.
      */
     wait: function wait(interruptable, timeout) {
-        let end = Date.now() + timeout;
-        util.waitFor(function () !this.incomplete || (this.timeout && Date.now() > end),
-                     this);
+        util.waitFor(function () !this.incomplete, this, timeout);
         return this.incomplete;
     }
 }, {
diff --git a/common/modules/util.jsm b/common/modules/util.jsm
index 01fce1ae..4459f597 100644
--- a/common/modules/util.jsm
+++ b/common/modules/util.jsm
@@ -1526,8 +1526,9 @@ var Util = Module("Util", XPCOM([Ci.nsIObserver, Ci.nsISupportsWeakReference]),
             this.yielders--;
         }
     },
-    waitFor: function waitFor(test, self, interruptable) {
-        while (!test.call(self))
+    waitFor: function waitFor(test, self, timeout, interruptable) {
+        let end = timeout && Date.now() + timeout;
+        while ((!end || Date.now() < end) && !test.call(self))
             this.threadYield(false, interruptable);
     },