diff --git a/grammars.yml b/grammars.yml
index fc1d510f..75203406 100644
--- a/grammars.yml
+++ b/grammars.yml
@@ -26,13 +26,13 @@ https://github.com/AlanQuatermain/go-tmbundle:
 - source.go
 https://github.com/Anomareh/PHP-Twig.tmbundle:
 - text.html.twig
-https://github.com/Cirru/sublime-cirru/raw/master/Cirru.tmLanguage:
+https://github.com/Cirru/sublime-cirru:
 - source.cirru
 https://github.com/Cykey/Sublime-Logos:
 - source.logos
-https://github.com/Drako/SublimeBrainfuck/raw/master/Brainfuck.tmLanguage:
+https://github.com/Drako/SublimeBrainfuck:
 - source.bf
-https://github.com/JohnNilsson/awk-sublime/raw/master/AWK.tmLanguage:
+https://github.com/JohnNilsson/awk-sublime:
 - source.awk
 https://github.com/JonBons/Sublime-SQF-Language:
 - source.sqf
@@ -46,7 +46,7 @@ https://github.com/Red-Nova-Technologies/autoitv3-tmbundle:
 - source.autoit.3
 https://github.com/SalGnt/Sublime-VimL:
 - source.viml
-https://github.com/Shammah/boo-sublime/raw/master/Boo.tmLanguage:
+https://github.com/Shammah/boo-sublime:
 - source.boo
 https://github.com/SublimeText/ColdFusion:
 - source.cfscript
@@ -74,6 +74,8 @@ https://github.com/aroben/ruby.tmbundle@4636a3023153c3034eb6ffc613899ba9cf33b41f
 - text.html.erb
 https://github.com/asbjornenge/Docker.tmbundle:
 - source.dockerfile
+https://github.com/atmarksharp/jasmin-sublime:
+- source.jasmin
 https://github.com/atom/language-clojure:
 - source.clojure
 https://github.com/atom/language-coffee-script:
@@ -84,7 +86,7 @@ https://github.com/atom/language-csharp:
 - source.csx
 - source.nant-build
 https://github.com/atom/language-gfm:
-- text.html.markdown
+- source.gfm
 https://github.com/atom/language-javascript:
 - source.js
 - source.js.regexp
@@ -110,7 +112,8 @@ https://github.com/brandonwamboldt/sublime-nginx:
 - source.nginx
 https://github.com/bro/bro-sublime:
 - source.bro
-https://github.com/carsonoid/sublime_man_page_support/raw/master/man-groff.tmLanguage:
+https://github.com/carsonoid/sublime_man_page_support:
+- source.man
 - text.groff
 https://github.com/ccreutzig/sublime-MuPAD:
 - source.mupad
@@ -127,7 +130,7 @@ https://github.com/clemos/haxe-sublime-bundle:
 https://github.com/cucumber/cucumber-tmbundle:
 - source.ruby.rspec.cucumber.steps
 - text.gherkin.feature
-https://github.com/daaain/Handlebars/raw/master/Handlebars.tmLanguage:
+https://github.com/daaain/Handlebars:
 - text.html.handlebars
 https://github.com/davidpeckham/powershell.tmbundle:
 - source.powershell
@@ -138,9 +141,12 @@ https://github.com/elixir-lang/elixir-tmbundle:
 - source.elixir
 - text.elixir
 - text.html.elixir
+https://github.com/eregon/oz-tmbundle/raw/master/Syntaxes/Oz.tmLanguage:
+- source.oz
 https://github.com/ericzou/ebundles/raw/master/Bundles/MSDOS%20batch%20file.tmbundle/Syntaxes/MSDOS%20batch%20file.tmLanguage:
 - source.dosbatch
-https://github.com/euler0/sublime-glsl/raw/master/GLSL.tmLanguage:
+https://github.com/euler0/sublime-glsl:
+- source.essl
 - source.glsl
 https://github.com/fancy-lang/fancy-tmbundle:
 - source.fancy
@@ -148,27 +154,32 @@ https://github.com/fsharp/fsharpbinding:
 - source.fsharp
 https://github.com/gingerbeardman/monkey.tmbundle:
 - source.monkey
-https://github.com/guillermooo/dart-sublime-bundle/raw/master/Dart.tmLanguage:
+https://github.com/guillermooo/dart-sublime-bundle:
 - source.dart
-https://github.com/harrism/sublimetext-cuda-cpp/raw/master/cuda-c%2B%2B.tmLanguage:
+- source.pubspec
+- text.dart-doccomments
+https://github.com/harrism/sublimetext-cuda-cpp:
 - source.cuda-c++
 https://github.com/hww3/pike-textmate:
 - source.pike
-https://github.com/jeancharles-roger/ceylon-sublimetext/raw/master/Ceylon.tmLanguage:
+https://github.com/jeancharles-roger/ceylon-sublimetext:
+- module.ceylon
 - source.ceylon
 https://github.com/jfairbank/Sublime-Text-2-OpenEdge-ABL:
 - source.abl
 https://github.com/jhasse/sublime-rust:
 - source.rust
-https://github.com/johanasplund/sublime-befunge/raw/master/Befunge-93.tmLanguage:
+https://github.com/johanasplund/sublime-befunge:
 - source.befunge
 https://github.com/joshaven/RDoc.tmbundle:
 - text.rdoc
-https://github.com/jpcamara/Textmate-Gosu-Bundle/raw/master/Gosu.tmbundle/Syntaxes/Gosu.tmLanguage:
+https://github.com/jpcamara/Textmate-Gosu-Bundle:
 - source.gosu.2
 https://github.com/kswedberg/jquery-tmbundle:
 - source.js.jquery
-https://github.com/laughedelic/sublime-idris/raw/master/Idris.tmLanguage:
+https://github.com/l15n/fish-tmbundle:
+- source.fish
+https://github.com/laughedelic/sublime-idris:
 - source.idris
 https://github.com/lavrton/sublime-better-typescript:
 - source.ts
@@ -196,14 +207,15 @@ https://github.com/mgalloy/idl.tmbundle:
 - text.idl-idldoc
 https://github.com/michaeledgar/protobuf-tmbundle:
 - source.protobuf
-https://github.com/mkolosick/Sublime-Coq/raw/master/Coq.tmLanguage:
+https://github.com/mkolosick/Sublime-Coq:
 - source.coq
 https://github.com/mokus0/Agda.tmbundle:
 - source.agda
 https://github.com/nanoant/Julia.tmbundle:
 - source.julia
-https://github.com/nanoant/assembly.tmbundle/raw/master/Syntaxes/objdump%20C%2B%2B.tmLanguage:
+https://github.com/nanoant/assembly.tmbundle:
 - objdump.x86asm
+- source.x86asm
 https://github.com/nilium/ooc.tmbundle:
 - source.ooc
 https://github.com/paulmillr/LiveScript.tmbundle:
@@ -217,6 +229,8 @@ https://github.com/pvl/abap.tmbundle:
 https://github.com/scalate/Scalate.tmbundle:
 - source.scaml
 - text.html.ssp
+https://github.com/sebgod/mercury-tmlanguage:
+- source.mercury
 https://github.com/shadanan/mathematica-tmbundle:
 - source.mathematica
 https://github.com/shellderp/sublime-robot-plugin:
@@ -229,8 +243,9 @@ https://github.com/skozlovf/Sublime-QML:
 - source.qml
 https://github.com/slash-lang/Slash.tmbundle:
 - text.html.slash
-https://github.com/slavapestov/factor/raw/master/misc/Factor.tmbundle/Syntaxes/Factor.tmLanguage:
+https://github.com/slavapestov/factor:
 - source.factor
+- text.html.factor
 https://github.com/slim-template/ruby-slim.tmbundle:
 - text.slim
 https://github.com/staltz/SublimeXtend:
@@ -240,6 +255,8 @@ https://github.com/statatmbundle/Stata.tmbundle:
 - source.stata
 https://github.com/technosophos/Vala-TMBundle:
 - source.vala
+https://github.com/tenbits/sublime-mask/raw/release/Syntaxes/mask.tmLanguage:
+- source.mask
 https://github.com/textmate/ant.tmbundle:
 - text.xml.ant
 https://github.com/textmate/antlr.tmbundle:
@@ -254,10 +271,6 @@ https://github.com/textmate/asp.tmbundle:
 - text.html.asp
 https://github.com/textmate/bison.tmbundle:
 - source.bison
-https://github.com/vmg/c.tmbundle:
-- source.c
-- source.c++
-- source.c.platform
 https://github.com/textmate/capnproto.tmbundle:
 - source.capnp
 https://github.com/textmate/cmake.tmbundle:
@@ -410,25 +423,17 @@ https://github.com/textmate/xml.tmbundle:
 - text.xml.xsl
 https://github.com/tomas-stefano/smalltalk-tmbundle:
 - source.smalltalk
-https://github.com/vic/ioke-outdated/raw/master/share/TextMate/Ioke.tmbundle/Syntaxes/Ioke.tmLanguage:
+https://github.com/vic/ioke-outdated:
 - source.ioke
 https://github.com/vkostyukov/kotlin-sublime-package:
 - source.Kotlin
+https://github.com/vmg/c.tmbundle:
+- source.c
+- source.c++
+- source.c.platform
 https://github.com/vmg/zephir-sublime:
 - source.php.zephir
 https://github.com/whitequark/llvm.tmbundle:
 - source.llvm
 https://github.com/wmertens/sublime-nix:
 - source.nix
-https://raw.githubusercontent.com/eregon/oz-tmbundle/master/Syntaxes/Oz.tmLanguage:
-- source.oz
-https://raw.githubusercontent.com/sebgod/mercury-tmlanguage/master/Mercury.tmLanguage:
-- source.mercury
-https://raw.githubusercontent.com/tenbits/sublime-mask/release/Syntaxes/mask.tmLanguage:
-- source.mask
-https://github.com/l15n/fish-tmbundle:
-- source.fish
-https://raw.githubusercontent.com/andik/IDL-Syntax/master/IDL.tmLanguage:
-- source.webidl
-https://raw.githubusercontent.com/atmarksharp/jasmin-sublime/master/Jasmin.tmLanguage:
-- source.jasmin
diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index bddc4568..d69b072a 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -1725,7 +1725,7 @@ Markdown:
   - .mkdn
   - .mkdown
   - .ron
-  tm_scope: text.html.markdown
+  tm_scope: source.gfm
 
 Mask:
   type: markup
@@ -3057,7 +3057,7 @@ WebIDL:
   type: programming
   extensions:
   - .webidl
-  tm_scope: source.webidl
+  tm_scope: none
   ace_mode: text
 
 XC:
diff --git a/test/test_grammars.rb b/test/test_grammars.rb
new file mode 100644
index 00000000..96fdb667
--- /dev/null
+++ b/test/test_grammars.rb
@@ -0,0 +1,13 @@
+require_relative "./helper"
+
+class TestGrammars < Test::Unit::TestCase
+  def setup
+    @grammars = YAML.load(File.read(File.expand_path("../../grammars.yml", __FILE__)))
+  end
+
+  def test_no_duplicate_scopes
+    scopes = @grammars.values.flatten
+    duplicates = scopes.group_by { |s| s }.select { |k, v| v.length > 1 }.map(&:first)
+    assert duplicates.empty?, "The following scopes appear in grammars.yml more than once:\n#{duplicates.sort.join("\n")}"
+  end
+end
diff --git a/test/test_pedantic.rb b/test/test_pedantic.rb
index be8ce063..9e35a8f2 100644
--- a/test/test_pedantic.rb
+++ b/test/test_pedantic.rb
@@ -3,6 +3,7 @@ require_relative "./helper"
 class TestPedantic < Test::Unit::TestCase
   filename = File.expand_path("../../lib/linguist/languages.yml", __FILE__)
   LANGUAGES = YAML.load(File.read(filename))
+  GRAMMARS = YAML.load(File.read(File.expand_path("../../grammars.yml", __FILE__)))
 
   def test_language_names_are_sorted
     assert_sorted LANGUAGES.keys
@@ -21,6 +22,16 @@ class TestPedantic < Test::Unit::TestCase
     end
   end
 
+  def test_grammars_are_sorted
+    assert_sorted GRAMMARS.keys
+  end
+
+  def test_scopes_are_sorted
+    GRAMMARS.values.each do |scopes|
+      assert_sorted scopes
+    end
+  end
+
   def assert_sorted(list)
     list.each_cons(2) do |previous, item|
       flunk "#{previous} should come after #{item}" if previous > item