diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index a470f579..61e790ba 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -217,6 +217,7 @@ CoffeeScript:
   aliases:
   - coffee
   extensions:
+  - ._coffee
   - .coffee
   filenames:
   - Cakefile
@@ -586,6 +587,7 @@ JavaScript:
   - node
   primary_extension: .js
   extensions:
+  - ._js
   - .bones
   - .jake
   - .js
diff --git a/test/test_language.rb b/test/test_language.rb
index 5186af52..90a5e26a 100644
--- a/test/test_language.rb
+++ b/test/test_language.rb
@@ -252,6 +252,11 @@ class TestLanguage < Test::Unit::TestCase
     assert_equal Language['PHP'], Language.find_by_extension('php5')
     assert_equal Language['PowerShell'], Language.find_by_extension('psm1')
     assert_equal Language['PowerShell'], Language.find_by_extension('ps1')
+
+    # Aliases for Streamline.js ( https://github.com/Sage/streamlinejs )
+    assert_equal Language['JavaScript'], Language.find_by_extension('_js')
+    assert_equal Language['CoffeeScript'], Language.find_by_extension('_coffee')
+
     assert_nil Language.find_by_extension('.nkt')
   end