diff --git a/mozilla/toolkit/components/console/content/console.js b/mozilla/toolkit/components/console/content/console.js
index 1f6e7e6892b..122d1efc4a0 100644
--- a/mozilla/toolkit/components/console/content/console.js
+++ b/mozilla/toolkit/components/console/content/console.js
@@ -106,8 +106,9 @@ function onEvalKeyPress(aEvent)
 function evaluateTypein()
 {
   var code = gTextBoxEval.value;
-  var iframe = document.getElementById("Evaluator");
-  iframe.contentDocument.location = "javascript: " + encodeURIComponent(code);
+  var evaluator = document.getElementById("Evaluator").contentWindow;
+  evaluator.location = "about:blank"; // reset the iframe
+  evaluator.location = "javascript: " + encodeURIComponent(code);
 }
 
 function displayResult()
diff --git a/mozilla/xpfe/components/console/resources/content/console.js b/mozilla/xpfe/components/console/resources/content/console.js
index d681bdd612a..583f36e4771 100644
--- a/mozilla/xpfe/components/console/resources/content/console.js
+++ b/mozilla/xpfe/components/console/resources/content/console.js
@@ -134,8 +134,9 @@ function onEvalKeyPress(aEvent)
 function evaluateTypein()
 {
   var code = document.getElementById("TextboxEval").value;
-  var iframe = document.getElementById("Evaluator");
-  iframe.contentDocument.location = "javascript: " + encodeURIComponent(code);
+  var evaluator = document.getElementById("Evaluator").contentWindow;
+  evaluator.location = "about:blank"; // reset the iframe
+  evaluator.location = "javascript: " + encodeURIComponent(code);
 }
 
 function displayResult()