diff --git a/mingw-w64-firefox/0013-MinGW-w64-Disable-TabletMode-stuff.patch b/mingw-w64-firefox/0013-MinGW-w64-Disable-TabletMode-stuff.patch
index 89d03154d4..c3a989c5b8 100644
--- a/mingw-w64-firefox/0013-MinGW-w64-Disable-TabletMode-stuff.patch
+++ b/mingw-w64-firefox/0013-MinGW-w64-Disable-TabletMode-stuff.patch
@@ -4,7 +4,7 @@
  #include "nsString.h"
  #include "nsIWidget.h"
  
-+#if defined(__MINGW32_MAJOR_VERSION)
++#if defined(__MINGW64_VERSION_MAJOR)
 +/* MinGW-w64 doesn't have support for this WRL stuff yet:
 +   https://msdn.microsoft.com/en-us/library/hh438466(v=vs.110).aspx */
 +
@@ -46,4 +46,4 @@
    return NS_OK;
  }
  
-+#endif /* defined(__MINGW32_MAJOR_VERSION) */
++#endif /* defined(__MINGW64_VERSION_MAJOR) */
diff --git a/mingw-w64-firefox/0021-MinGW-w64-Dont-redefine-MFVideoFormat_VPn0.patch b/mingw-w64-firefox/0021-MinGW-w64-Dont-redefine-MFVideoFormat_VPn0.patch
new file mode 100644
index 0000000000..59c0a504ae
--- /dev/null
+++ b/mingw-w64-firefox/0021-MinGW-w64-Dont-redefine-MFVideoFormat_VPn0.patch
@@ -0,0 +1,19 @@
+--- firefox-41.0.1/dom/media/platforms/wmf/WMFVideoMFTManager.cpp.orig	2015-09-29 22:45:02.000000000 +0100
++++ firefox-41.0.1/dom/media/platforms/wmf/WMFVideoMFTManager.cpp	2015-10-02 11:17:05.962703900 +0100
+@@ -30,6 +30,8 @@
+ using mozilla::layers::LayerManager;
+ using mozilla::layers::LayersBackend;
+ 
++/* MinGW-w64's mfapi.h defines these already. */
++#if !defined(__MINGW64_VERSION_MAJOR)
+ const GUID MFVideoFormat_VP80 =
+ {
+   0x30385056,
+@@ -45,6 +47,7 @@
+   0x0010,
+   {0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
+ };
++#endif /* !defined(__MINGW64_VERSION_MAJOR) */
+ 
+ const CLSID CLSID_WebmMfVp8Dec =
+ {
diff --git a/mingw-w64-firefox/PKGBUILD b/mingw-w64-firefox/PKGBUILD
index e3f700c632..292fb231fb 100644
--- a/mingw-w64-firefox/PKGBUILD
+++ b/mingw-w64-firefox/PKGBUILD
@@ -77,7 +77,7 @@ path_conv_for_make() {
 _realname=firefox
 pkgbase=mingw-w64-${_realname}
 pkgname=("${MINGW_PACKAGE_PREFIX}-${_realname}")
-pkgver=41.0b6
+pkgver=41.0.1
 pkgrel=1
 pkgdesc='Mozilla Firefox (mingw-w64)'
 groups=("${MINGW_PACKAGE_PREFIX}")
@@ -112,13 +112,14 @@ source=("http://ftp.mozilla.org/pub/mozilla.org/${_realname}/releases/${pkgver}/
         "0018-MSYS2-Allow-make-install.patch"
         "0019-Bug-id-1163452-MSYS2-Dont-MOZ_ASSERT-when-stdout-is-same-as-stderr.patch"
         "0020-gmp-clearkey-include-atomic-header.patch"
+        "0021-MinGW-w64-Dont-redefine-MFVideoFormat_VPn0.patch"
         "debugging.patch"
         "mozconfig.x86_64"
         "mozconfig.i686"
         "config.sub"
         "config.guess")
 noextract=("${_realname}-${pkgver}.source.tar.xz")
-sha1sums=('6b4c0d3a9a228b43d9682d57f74a1132f92dd329'
+sha1sums=('4f6bf34b7b286e033f401d7d4112ec6310577aae'
           '6c018e4ac903180f5f65492241502842dc1c035a'
           'c4e841bf724a1ff907592c8a11ba9683568acfd5'
           '1c0810fbfd6f336eec81e236c89c6c9ca0e79290'
@@ -133,7 +134,7 @@ sha1sums=('6b4c0d3a9a228b43d9682d57f74a1132f92dd329'
           '12385ab4cb659f712f3a3a93248741d299048b9c'
           '4553ac6631d56bc251ffd6cbc503002c6835c9de'
           'de9fb13afd011710349c868f2bd60f3508986905'
-          '543812a70510a08cf16af2e86d2e0fb79af26c14'
+          '1da4ea7929176f545f9f20e00109d93bc9c4fd12'
           '7e36fe8fcca2730cf55a2703b50d998b93af3b7e'
           '7dcb0ea5e54ffb08cc9afa495b13e42d058ecbbd'
           'bacec1492cb54096f7483b192918050e7cb1de1d'
@@ -141,6 +142,7 @@ sha1sums=('6b4c0d3a9a228b43d9682d57f74a1132f92dd329'
           'e939e9722fd0cb70a7bd5e705b37bd47045e9647'
           '20a6613a688c2e7cb95a6faae49974e452dba8de'
           '7f23896aeca52cd7bd3a038c5b5fd4eb68c90923'
+          '6d8c68944d14f04948dc31a558cc7a2d25e9df12'
           'c2a0ed20a82d212bb4aa84cb2f294be3ba0bb859'
           '02befff9986a31bbc4ad74a8c0125e84f29fcb40'
           '9f4a4161fd23ba603c3e8140b322e732a46efffc'
@@ -193,6 +195,7 @@ prepare() {
   patch -p1 -i "${srcdir}"/0018-MSYS2-Allow-make-install.patch
   patch -p1 -i "${srcdir}"/0019-Bug-id-1163452-MSYS2-Dont-MOZ_ASSERT-when-stdout-is-same-as-stderr.patch
   patch -p1 -i "${srcdir}"/0020-gmp-clearkey-include-atomic-header.patch
+  patch -p1 -i "${srcdir}"/0021-MinGW-w64-Dont-redefine-MFVideoFormat_VPn0.patch
   # patch -p1 -i "${srcdir}"/debugging.patch
 
   find . -name config.sub -exec cp "${srcdir}"/config.sub {} \;
@@ -278,3 +281,19 @@ package() {
   # ArchLinux uses (but this fails on MSYS2):
   # "${_make}" -k -C ${PWD}/${_builddir} DESTDIR="${pkgdir}" INSTALL_SDK= install -k
 }
+
+# Trying to figure out why I'm not getting debugging info in xul.dll:
+# (do_main in firefox-41.0.1/browser/app/nsBrowserApp.cpp is the last thing with debug info)
+# Crash happens in firefox-41.0.1/js/src/jit/BaselineJIT.cpp .. in .. firefox-41.0.1/obj-i686-w64-mingw32/js/src/Unified_cpp_js_src3.cpp .. in .. libjs_static.a
+# c++ -mwindows -o nsBrowserApp.o -c   -DFIREFOX_ICO='"../../dist/branding/firefox.ico"' -DDOCUMENT_ICO='"../../dist/branding/document.ico"' -DNEWWINDOW_ICO='"../../dist/branding/newwindow.ico"' -DNEWTAB_ICO='"../../dist/branding/newtab.ico"' -DPBMODE_ICO='"../../dist/branding/pbmode.ico"'  -DXPCOM_GLUE -DAPP_VERSION='41.0.1' -DMOZ_PHOENIX -DAB_CD=en-US -DNO_NSPR_10_SUPPORT -IE:/m2/repo/mingw-w64-firefox/src/firefox-41.0.1/browser/app -I. -IE:/m2/repo/mingw-w64-firefox/src/firefox-41.0.1/obj-i686-w64-mingw32/build -IE:/m2/repo/mingw-w64-firefox/src/firefox-41.0.1/toolkit/xre -IE:/m2/repo/mingw-w64-firefox/src/firefox-41.0.1/xpcom/base -IE:/m2/repo/mingw-w64-firefox/src/firefox-41.0.1/xpcom/build -I../../dist/include   -IE:/m2/repo/mingw-w64-firefox/src/firefox-41.0.1/obj-i686-w64-mingw32/dist/include/nspr -IE:/m2/repo/mingw-w64-firefox/src/firefox-41.0.1/obj-i686-w64-mingw32/dist/include/nss         -D_FORTIFY_SOURCE=2 -D__USE_MINGW_ANSI_STDIO=1 -DMOZILLA_CLIENT -include ../../mozilla-config.h -MD -MP -MF .deps/nsBrowserApp.o.pp -D_FORTIFY_SOURCE=2 -D__USE_MINGW_ANSI_STDIO=1 -Wall -Wempty-body -Woverloaded-virtual -Wsign-compare -Wwrite-strings -Wno-invalid-offsetof -Wcast-align -Wno-format -march=i686 -mtune=generic -O2 -pipe -ggdb -Og -ggdb -Og -fno-exceptions -fno-strict-aliasing -mms-bitfields -mstackrealign -fno-keep-inline-dllexport -fno-rtti -fno-exceptions -fno-math-errno -std=gnu++0x -pthread -pipe  -DDEBUG -DTRACING -g -fno-omit-frame-pointer      E:/m2/repo/mingw-w64-firefox/src/firefox-41.0.1/browser/app/nsBrowserApp.cpp
+# E:/m2/repo/mingw-w64-firefox/src/firefox-41.0.1/obj-i686-w64-mingw32/_virtualenv/bin/python.exe E:/m2/repo/mingw-w64-firefox/src/firefox-41.0.1/config/expandlibs_exec.py --uselist --  c++ -mwindows -o firefox.exe -D_FORTIFY_SOURCE=2 -D__USE_MINGW_ANSI_STDIO=1 -Wall -Wempty-body -Woverloaded-virtual -Wsign-compare -Wwrite-strings -Wno-invalid-offsetof -Wcast-align -Wno-format -march=i686 -mtune=generic -O2 -pipe -ggdb -Og -ggdb -Og -fno-exceptions -fno-strict-aliasing -mms-bitfields -mstackrealign -fno-keep-inline-dllexport -fno-rtti -fno-exceptions -fno-math-errno -std=gnu++0x -pthread -pipe  -DDEBUG -DTRACING -g -fno-omit-frame-pointer   nsBrowserApp.o ./module.res -mconsole -lpthread -pipe -Wl,--build-id -Wl,--enable-stdcall-fixup -Wl,--large-address-aware   -DELAYLOAD:mozglue.dll   ../../xpcom/glue/standalone/staticruntime/libxpcomglue_staticruntime.a ../../memory/fallible/libfallible.a  ../../mozglue/build/libmozglue.a  -luuid -lgdi32 -lwinmm -lwsock32 -luserenv -lsecur32 -lnetapi32 -ldelayimp  
+#
+# /mingw32/bin/objdump -p ./js/src/Unified_cpp_js_src3.o | less
+#  ./js/src/Unified_cpp_js_src3.o:     file format pe-i386
+# Characteristics 0x104
+#         line numbers stripped
+#         32 bit words
+#
+# c++ -mwindows -o Unified_cpp_js_src3.o -c   -DFFI_BUILDING -D_CRT_RAND_S -DEXPORT_JS_API -DJS_HAS_CTYPES -DDLL_PREFIX='""' -DDLL_SUFFIX='".dll"' -DAB_CD= -DNO_NSPR_10_SUPPORT -IE:/m2/repo/mingw-w64-firefox/src/firefox-41.0.1/js/src -I. -Ictypes/libffi/include -IE:/m2/repo/mingw-w64-firefox/src/firefox-41.0.1/intl/icu/source/common -IE:/m2/repo/mingw-w64-firefox/src/firefox-41.0.1/intl/icu/source/i18n -I../../dist/include   -IE:/m2/repo/mingw-w64-firefox/src/firefox-41.0.1/obj-i686-w64-mingw32/dist/include/nspr          -D_FORTIFY_SOURCE=2 -D__USE_MINGW_ANSI_STDIO=1 -DMOZILLA_CLIENT -include ../../js/src/js-confdefs.h -MD -MP -MF .deps/Unified_cpp_js_src3.o.pp -D_FORTIFY_SOURCE=2 -D__USE_MINGW_ANSI_STDIO=1 -Wall -Wsign-compare -Wtype-limits -Wno-invalid-offsetof -Wcast-align -Wno-format -march=i686 -mtune=generic -O2 -pipe -ggdb -Og -ggdb -Og -mms-bitfields -mstackrealign -fno-keep-inline-dllexport -fno-rtti -fno-exceptions -fno-math-errno -std=gnu++0x -pthread -pipe  -DDEBUG -DTRACING -g -fno-omit-frame-pointer      E:/m2/repo/mingw-w64-firefox/src/firefox-41.0.1/obj-i686-w64-mingw32/js/src/Unified_cpp_js_src3.cpp
+# E:/m2/repo/mingw-w64-firefox/src/firefox-41.0.1/obj-i686-w64-mingw32/_virtualenv/bin/python.exe E:/m2/repo/mingw-w64-firefox/src/firefox-41.0.1/config/expandlibs_exec.py --extract -- ar crs libjs_static.a RegExp.o CTypes.o Library.o Parser.o ExecutableAllocatorWin.o jsarray.o jsatom.o jsmath.o jsutil.o pm_stub.o TraceLogging.o TraceLoggingGraph.o TraceLoggingTypes.o Unified_cpp_js_src0.o Unified_cpp_js_src1.o Unified_cpp_js_src10.o Unified_cpp_js_src11.o Unified_cpp_js_src12.o Unified_cpp_js_src2.o Unified_cpp_js_src3.o Unified_cpp_js_src4.o Unified_cpp_js_src5.o Unified_cpp_js_src6.o Unified_cpp_js_src7.o Unified_cpp_js_src8.o Unified_cpp_js_src9.o ../../config/external/ffi/libffi.a ../../config/external/nspr/libnspr.a ../../config/external/zlib/libzlib.a 
+