--- a/.clang-format-ignore
+++ b/.clang-format-ignore
@@ -1,136 +1,136 @@
 # Uses the LLVM coding style
-build/clang-plugin/.*
+^build/clang-plugin/.*
 # The two templates cannot be formatted
-config/gcc-stl-wrapper.template.h
-config/msvc-stl-wrapper.template.h
-dom/base/test/.*
-dom/bindings/test/.*
-dom/media/gtest/.*
-gfx/testsd/.*
-image/test/.*
-ipc/ipdl/test/.*
-ipc/testshell/.*
-js/src/jsapi-tests/.*
+^config/gcc-stl-wrapper.template.h
+^config/msvc-stl-wrapper.template.h
+^dom/base/test/.*
+^dom/bindings/test/.*
+^dom/media/gtest/.*
+^gfx/testsd/.*
+^image/test/.*
+^ipc/ipdl/test/.*
+^ipc/testshell/.*
+^js/src/jsapi-tests/.*
 # See bug 1395584
-js/src/vm/Opcodes.h
+^js/src/vm/Opcodes.h
 # Ignored because of bug 1342657
-layout/style/nsCSSPropAliasList.h
+^layout/style/nsCSSPropAliasList.h
 # Ignored because of bug 1342657
-layout/style/nsCSSPropList.h
-media/mtransport/test/.*
-mfbt/tests/.*
-storage/test/.*
-testing/gtest/.*
-tools/profiler/tests/.*
-uriloader/exthandler/tests/.*
+^layout/style/nsCSSPropList.h
+^media/mtransport/test/.*
+^mfbt/tests/.*
+^storage/test/.*
+^testing/gtest/.*
+^tools/profiler/tests/.*
+^uriloader/exthandler/tests/.*
 # JNI code is generated
-widget/android/GeneratedJNINatives.h
-widget/android/GeneratedJNIWrappers.cpp
-widget/android/GeneratedJNIWrappers.h
-widget/android/fennec/FennecJNINatives.h
-widget/android/fennec/FennecJNIWrappers.cpp
-widget/android/fennec/FennecJNIWrappers.h
-widget/tests/.*
-xpcom/glue/tests/.*
-xpcom/tests/.*
+^widget/android/GeneratedJNINatives.h
+^widget/android/GeneratedJNIWrappers.cpp
+^widget/android/GeneratedJNIWrappers.h
+^widget/android/fennec/FennecJNINatives.h
+^widget/android/fennec/FennecJNIWrappers.cpp
+^widget/android/fennec/FennecJNIWrappers.h
+^widget/tests/.*
+^xpcom/glue/tests/.*
+^xpcom/tests/.*
 
 # Generated from ./tools/rewriting/ThirdPartyPaths.txt
-# awk '{print ""$1".*"}' ./tools/rewriting/ThirdPartyPaths.txt
-browser/components/translation/cld2/.*
-browser/extensions/mortar/ppapi/.*
-db/sqlite3/src/.*
-extensions/spellcheck/hunspell/src/.*
-gfx/angle/.*
-gfx/cairo/.*
-gfx/graphite2/.*
-gfx/harfbuzz/.*
-gfx/ots/.*
-gfx/qcms/.*
-gfx/sfntly/.*
-gfx/skia/.*
-gfx/vr/openvr/.*
-gfx/webrender.*
-gfx/webrender_api.*
-gfx/ycbcr/.*
-intl/hyphenation/hyphen/.*
-intl/icu/.*
-ipc/chromium/.*
-js/src/ctypes/libffi/.*
-js/src/dtoa.c.*
-js/src/jit/arm64/vixl/.*
-media/ffvpx/.*
-media/gmp-clearkey/0.1/openaes/.*
-media/kiss_fft/.*
-media/libav/.*
-media/libcubeb/.*
-media/libjpeg/.*
-media/libmkv/.*
-media/libnestegg/.*
-media/libogg/.*
-media/libopus/.*
-media/libpng/.*
-media/libsoundtouch/.*
-media/libspeex_resampler/.*
-media/libstagefright/.*
-media/libtheora/.*
-media/libtremor/.*
-media/libvorbis/.*
-media/libvpx/.*
-media/libyuv/.*
-media/mtransport/third_party/.*
-media/openmax_dl/.*
-media/sphinxbase/.*
-media/webrtc/signaling/src/sdp/sipcc/.*
-media/webrtc/trunk/.*
-mfbt/decimal/.*
-mfbt/double-conversion/double-conversion/.*
-mobile/android/geckoview/src/thirdparty/.*
-mobile/android/thirdparty/.*
-modules/brotli/.*
-modules/fdlibm/.*
-modules/freetype2/.*
-modules/libbz2/.*
-modules/libmar/.*
-modules/pdfium/.*
-modules/woff2/.*
-modules/zlib/.*
-netwerk/sctp/src/.*
-netwerk/srtp/src/.*
-nsprpub/.*
-other-licenses/.*
-parser/expat/.*
-security/nss/.*
-security/sandbox/chromium/.*
-testing/gtest/gmock/.*
-testing/gtest/gtest/.*
-testing/talos/talos/tests/canvasmark/.*
-testing/talos/talos/tests/dromaeo/.*
-testing/talos/talos/tests/kraken/.*
-testing/talos/talos/tests/v8_7/.*
-third_party/aom/.*
-third_party/python/blessings/.*
-third_party/python/configobj/.*
-third_party/python/futures/.*
-third_party/python/jsmin/.*
-third_party/python/mock-*/.*
-third_party/python/psutil/.*
-third_party/python/py/.*
-third_party/python/pyasn1/.*
-third_party/python/pyasn1-modules/.*
-third_party/python/PyECC/.*
-third_party/python/pytest/.*
-third_party/python/pytoml/.*
-third_party/python/pyyaml/.*
-third_party/python/redo/.*
-third_party/python/requests/.*
-third_party/python/rsa/.*
-third_party/python/six/.*
-third_party/python/which/.*
-third_party/rust/.*
-toolkit/components/jsoncpp/.*
-toolkit/components/lz4/.*
-toolkit/components/protobuf/.*
-toolkit/components/url-classifier/chromium/.*
-toolkit/components/url-classifier/protobuf/.*
-toolkit/crashreporter/google-breakpad/.*
-tools/fuzzing/libfuzzer.*
+# awk '{print "^"$1".*"}' ./tools/rewriting/ThirdPartyPaths.txt
+^browser/components/translation/cld2/.*
+^browser/extensions/mortar/ppapi/.*
+^db/sqlite3/src/.*
+^extensions/spellcheck/hunspell/src/.*
+^gfx/angle/.*
+^gfx/cairo/.*
+^gfx/graphite2/.*
+^gfx/harfbuzz/.*
+^gfx/ots/.*
+^gfx/qcms/.*
+^gfx/sfntly/.*
+^gfx/skia/.*
+^gfx/vr/openvr/.*
+^gfx/webrender.*
+^gfx/webrender_api.*
+^gfx/ycbcr/.*
+^intl/hyphenation/hyphen/.*
+^intl/icu/.*
+^ipc/chromium/.*
+^js/src/ctypes/libffi/.*
+^js/src/dtoa.c.*
+^js/src/jit/arm64/vixl/.*
+^media/ffvpx/.*
+^media/gmp-clearkey/0.1/openaes/.*
+^media/kiss_fft/.*
+^media/libav/.*
+^media/libcubeb/.*
+^media/libjpeg/.*
+^media/libmkv/.*
+^media/libnestegg/.*
+^media/libogg/.*
+^media/libopus/.*
+^media/libpng/.*
+^media/libsoundtouch/.*
+^media/libspeex_resampler/.*
+^media/libstagefright/.*
+^media/libtheora/.*
+^media/libtremor/.*
+^media/libvorbis/.*
+^media/libvpx/.*
+^media/libyuv/.*
+^media/mtransport/third_party/.*
+^media/openmax_dl/.*
+^media/sphinxbase/.*
+^media/webrtc/signaling/src/sdp/sipcc/.*
+^media/webrtc/trunk/.*
+^mfbt/decimal/.*
+^mfbt/double-conversion/double-conversion/.*
+^mobile/android/geckoview/src/thirdparty/.*
+^mobile/android/thirdparty/.*
+^modules/brotli/.*
+^modules/fdlibm/.*
+^modules/freetype2/.*
+^modules/libbz2/.*
+^modules/libmar/.*
+^modules/pdfium/.*
+^modules/woff2/.*
+^modules/zlib/.*
+^netwerk/sctp/src/.*
+^netwerk/srtp/src/.*
+^nsprpub/.*
+^other-licenses/.*
+^parser/expat/.*
+^security/nss/.*
+^security/sandbox/chromium/.*
+^testing/gtest/gmock/.*
+^testing/gtest/gtest/.*
+^testing/talos/talos/tests/canvasmark/.*
+^testing/talos/talos/tests/dromaeo/.*
+^testing/talos/talos/tests/kraken/.*
+^testing/talos/talos/tests/v8_7/.*
+^third_party/aom/.*
+^third_party/python/blessings/.*
+^third_party/python/configobj/.*
+^third_party/python/futures/.*
+^third_party/python/jsmin/.*
+^third_party/python/mock-*/.*
+^third_party/python/psutil/.*
+^third_party/python/py/.*
+^third_party/python/pyasn1/.*
+^third_party/python/pyasn1-modules/.*
+^third_party/python/PyECC/.*
+^third_party/python/pytest/.*
+^third_party/python/pytoml/.*
+^third_party/python/pyyaml/.*
+^third_party/python/redo/.*
+^third_party/python/requests/.*
+^third_party/python/rsa/.*
+^third_party/python/six/.*
+^third_party/python/which/.*
+^third_party/rust/.*
+^toolkit/components/jsoncpp/.*
+^toolkit/components/lz4/.*
+^toolkit/components/protobuf/.*
+^toolkit/components/url-classifier/chromium/.*
+^toolkit/components/url-classifier/protobuf/.*
+^toolkit/crashreporter/google-breakpad/.*
+^tools/fuzzing/libfuzzer.*

--- a/tools/mach_commands.py
+++ b/tools/mach_commands.py
@@ -299,18 +299,17 @@ class FormatProvider(MachCommandBase):
 
     def generate_path_list(self, paths):
         pathToThirdparty = os.path.join(self.topsrcdir, self._format_ignore_file)
         ignored_dir = []
         for line in open(pathToThirdparty):
             # Remove comments and empty lines
             if line.startswith('#') or len(line.strip()) == 0:
                 continue
-             # The regexp is to make sure we are managing relative paths
-            ignored_dir.append("^[\./]*" + line.rstrip())
+            ignored_dir.append(line.rstrip())
 
         # Generates the list of regexp
         ignored_dir_re = '(%s)' % '|'.join(ignored_dir)
         extensions = self._format_include_extensions
 
         path_list = []
         for f in paths:
             if re.match(ignored_dir_re, f):