diff --git a/browser/base/content/browser.js b/browser/base/content/browser.js
index c0c19619e578..be1b21ebd74e 100644
--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -6398,20 +6398,20 @@ function warnAboutClosingWindow() {
   // Figure out if there's at least one other browser window around.
   let e = Services.wm.getEnumerator("navigator:browser");
   let otherPBWindowExists = false;
-  let warnAboutClosingTabs = false;
+  let nonPopupPresent = false;
   while (e.hasMoreElements()) {
     let win = e.getNext();
     if (win != window) {
       if (isPBWindow && PrivateBrowsingUtils.isWindowPrivate(win))
         otherPBWindowExists = true;
       if (win.toolbar.visible)
-        warnAboutClosingTabs = true;
+        nonPopupPresent = true;
       // If the current window is not in private browsing mode we don't need to 
       // look for other pb windows, we can leave the loop when finding the 
       // first non-popup window. If however the current window is in private 
       // browsing mode then we need at least one other pb and one non-popup 
       // window to break out early.
-      if ((!isPBWindow || otherPBWindowExists) && warnAboutClosingTabs)
+      if ((!isPBWindow || otherPBWindowExists) && nonPopupPresent)
         break;
     }
   }
@@ -6426,7 +6426,8 @@ function warnAboutClosingWindow() {
     if (exitingCanceled.data)
       return false;
   }
-  if (warnAboutClosingTabs)
+
+  if (!isPBWindow && nonPopupPresent)
     return gBrowser.warnAboutClosingTabs(true);
 
   let os = Services.obs;
diff --git a/browser/base/content/test/Makefile.in b/browser/base/content/test/Makefile.in
index 20a6721dfd22..0cf195b166a1 100644
--- a/browser/base/content/test/Makefile.in
+++ b/browser/base/content/test/Makefile.in
@@ -313,6 +313,7 @@ _BROWSER_FILES = \
                  feed_tab.html \
                  browser_pluginCrashCommentAndURL.js \
                  pluginCrashCommentAndURL.html \
+                 browser_private_no_prompt.js \
                  $(NULL)
 
 # Disable test on Windows due to frequent failures (bug 841341)
diff --git a/browser/base/content/test/browser_private_no_prompt.js b/browser/base/content/test/browser_private_no_prompt.js
new file mode 100644
index 000000000000..17ab1b4373c8
--- /dev/null
+++ b/browser/base/content/test/browser_private_no_prompt.js
@@ -0,0 +1,13 @@
+function test() {
+  waitForExplicitFinish();
+  var privateWin = OpenBrowserWindow({private: true});
+  privateWin.addEventListener("load", function onload() {
+    privateWin.removeEventListener("load", onload, false);
+    ok(true, "Load listener called");
+
+    privateWin.BrowserOpenTab();
+    privateWin.BrowserTryToCloseWindow();
+    ok(true, "didn't prompt");
+    finish();                        
+  }, false);
+}
\ No newline at end of file