--- a/toolkit/devtools/server/actors/script.js
+++ b/toolkit/devtools/server/actors/script.js
@@ -462,16 +462,23 @@ ThreadActor.prototype = {
   get sources() {
     if (!this._sources) {
       this._sources = new ThreadSources(this, this._options.useSourceMaps,
                                         this._allowSource, this.onNewSource);
     }
     return this._sources;
   },
 
+  get youngestFrame() {
+    if (!this.state == "paused") {
+      return null;
+    }
+    return this.dbg.getNewestFrame();
+  },
+
   _prettyPrintWorker: null,
   get prettyPrintWorker() {
     if (!this._prettyPrintWorker) {
       this._prettyPrintWorker = new ChromeWorker(
         "resource://gre/modules/devtools/server/actors/pretty-print-worker.js");
 
       this._prettyPrintWorker.addEventListener(
         "error", this._onPrettyPrintError, false);
@@ -1174,20 +1181,16 @@ ThreadActor.prototype = {
                message: "Evaluation frame not found" };
     }
 
     if (!frame.environment) {
       return { error: "notDebuggee",
                message: "cannot access the environment of this frame." };
     }
 
-    // We'll clobber the youngest frame if the eval causes a pause, so
-    // save our frame now to be restored after eval returns.
-    // XXX: or we could just start using dbg.getNewestFrame() now that it
-    // works as expected.
     let youngest = this.youngestFrame;
 
     // Put ourselves back in the running state and inform the client.
     let resumedPacket = this._resumed();
     this.conn.send(resumedPacket);
 
     // Run the expression.
     // XXX: test syntax errors
@@ -1733,20 +1736,16 @@ ThreadActor.prototype = {
       for (let [,bp] of this._hiddenBreakpoints) {
         bp.onDelete();
       }
       this._hiddenBreakpoints.clear();
     }
 
     this._state = "paused";
 
-    // Save the pause frame (if any) as the youngest frame for
-    // stack viewing.
-    this.youngestFrame = aFrame;
-
     // Create the actor pool that will hold the pause actor and its
     // children.
     dbg_assert(!this._pausePool, "No pause pool should exist yet");
     this._pausePool = new ActorPool(this.conn);
     this.conn.addActorPool(this._pausePool);
 
     // Give children of the pause pool a quick link back to the
     // thread...
@@ -1778,17 +1777,16 @@ ThreadActor.prototype = {
   _resumed: function TA_resumed() {
     this._state = "running";
 
     // Drop the actors in the pause actor pool.
     this.conn.removeActorPool(this._pausePool);
 
     this._pausePool = null;
     this._pauseActor = null;
-    this.youngestFrame = null;
 
     return { from: this.actorID, type: "resumed" };
   },
 
   /**
    * Expire frame actors for frames that have been popped.
    *
    * @returns A list of actor IDs whose frames have been popped.
@@ -4019,17 +4017,17 @@ function getOffsetColumn(aOffset, aScrip
  * frame does not have a script, the location's properties are all null.
  *
  * @param Debugger.Frame aFrame
  *        The frame whose location we are getting.
  * @returns Object
  *          Returns an object of the form { url, line, column }
  */
 function getFrameLocation(aFrame) {
-  if (!aFrame.script) {
+  if (!aFrame || !aFrame.script) {
     return { url: null, line: null, column: null };
   }
   return {
     url: aFrame.script.url,
     line: aFrame.script.getOffsetLine(aFrame.offset),
     column: getOffsetColumn(aFrame.offset, aFrame.script)
   }
 }