diff --git a/firefox-1.5-thread-cleanup.patch b/firefox-1.5-thread-cleanup.patch
new file mode 100644
index 0000000..cfa3873
--- /dev/null
+++ b/firefox-1.5-thread-cleanup.patch
@@ -0,0 +1,28 @@
+Index: mozilla/xpcom/threads/nsThread.cpp
+===================================================================
+RCS file: /cvsroot/mozilla/xpcom/threads/nsThread.cpp,v
+retrieving revision 1.58.4.2
+diff -u -r1.58.4.2 nsThread.cpp
+--- mozilla/xpcom/threads/nsThread.cpp	1 Oct 2005 18:43:00 -0000	1.58.4.2
++++ mozilla/xpcom/threads/nsThread.cpp	7 May 2007 19:10:58 -0000
+@@ -470,9 +470,17 @@
+ nsThread::Shutdown()
+ {
+     if (gMainThread) {
+-        // XXX nspr doesn't seem to be calling the main thread's destructor
+-        // callback, so let's help it out:
+-        nsThread::Exit(NS_STATIC_CAST(nsThread*, gMainThread));
++        // In most recent versions of NSPR the main thread's destructor
++        // callback will get called.
++        // In older versions of NSPR it will not get called,
++        // (unless we call PR_Cleanup).
++        // Because of that we:
++        // - call the function ourselves
++        // - set the data pointer to NULL to ensure the function will
++        //   not get called again by NSPR
++        // The PR_SetThreadPrivate call does both of these.
++        // See also bugs 379550, 362768.
++        PR_SetThreadPrivate(kIThreadSelfIndex, NULL);
+         nsrefcnt cnt;
+         NS_RELEASE2(gMainThread, cnt);
+         NS_WARN_IF_FALSE(cnt == 0, "Main thread being held past XPCOM shutdown.");
diff --git a/firefox.spec b/firefox.spec
index 35ac0b2..b3fffdc 100644
--- a/firefox.spec
+++ b/firefox.spec
@@ -12,7 +12,7 @@
 Summary:        Mozilla Firefox Web browser.
 Name:           firefox
 Version:        2.0.0.4
-Release:        1%{?dist}
+Release:        2%{?dist}
 URL:            http://www.mozilla.org/projects/firefox/
 License:        MPL/LGPL
 Group:          Applications/Internet
@@ -62,6 +62,7 @@ Patch83:        firefox-1.5-pango-cursor-position.patch
 Patch84:        firefox-2.0-pango-printing.patch
 
 # Other
+Patch100:       firefox-1.5-thread-cleanup.patch
 Patch102:       firefox-1.5-theme-change.patch
 Patch104:       firefox-1.5-ppc64.patch
 
@@ -157,6 +158,7 @@ removed in favor of xulrunner-devel.
 %patch83 -p1 -b .pango-cursor-position
 %patch84 -p0 -b .pango-printing
 
+%patch100 -p1 -b .thread-cleanup
 %patch102 -p0 -b .theme-change
 %patch104 -p1 -b .ppc64
 
@@ -416,6 +418,9 @@ fi
 #---------------------------------------------------------------------
 
 %changelog
+* Sun Jun  3 2007 Christopher Aillon <caillon@redhat.com> 2.0.0.4-2
+- Properly clean up threads with newer NSPR
+
 * Wed May 30 2007 Christopher Aillon <caillon@redhat.com> 2.0.0.4-1
 - Final version