diff --git a/README.md b/README.md
index 70f97655a1..e2644acf2c 100644
--- a/README.md
+++ b/README.md
@@ -193,7 +193,7 @@ Use the `linguist-vendored` attribute to vendor or un-vendor paths:
 
 ```gitattributes
 special-vendored-path/* linguist-vendored
-jquery.js linguist-vendored=false
+jquery.js -linguist-vendored
 ```
 
 #### Documentation
@@ -205,7 +205,7 @@ Use the `linguist-documentation` attribute to mark or unmark paths as documentat
 
 ```gitattributes
 project-docs/* linguist-documentation
-docs/formatter.rb linguist-documentation=false
+docs/formatter.rb -linguist-documentation
 ```
 
 #### Generated code
@@ -218,7 +218,7 @@ As an added bonus, unlike vendored and documentation files, these files are supp
 Use the `linguist-generated` attribute to mark or unmark paths as generated.
 
 ```gitattributes
-Api.elm linguist-generated=true
+Api.elm linguist-generated
 ```
 
 #### Detectable
@@ -229,9 +229,9 @@ Languages of a different type (as defined in [`languages.yml`](/lib/linguist/lan
 Use the `linguist-detectable` attribute to mark or unmark paths as detectable:
 
 ```gitattributes
-*.kicad_pcb linguist-detectable=true
-*.sch linguist-detectable=true
-tools/export_bom.py linguist-detectable=false
+*.kicad_pcb linguist-detectable
+*.sch linguist-detectable
+tools/export_bom.py -linguist-detectable
 ```
 
 ### Using Emacs or Vim modelines
diff --git a/lib/linguist/lazy_blob.rb b/lib/linguist/lazy_blob.rb
index 389cc24303..98e75efb1f 100644
--- a/lib/linguist/lazy_blob.rb
+++ b/lib/linguist/lazy_blob.rb
@@ -38,24 +38,24 @@ def git_attributes
     end
 
     def documentation?
-      if attr = git_attributes['linguist-documentation']
-        boolean_attribute(attr)
+      if not git_attributes['linguist-documentation'].nil?
+        boolean_attribute(git_attributes['linguist-documentation'])
       else
         super
       end
     end
 
     def generated?
-      if attr = git_attributes['linguist-generated']
-        boolean_attribute(attr)
+      if not git_attributes['linguist-generated'].nil?
+        boolean_attribute(git_attributes['linguist-generated'])
       else
         super
       end
     end
 
     def vendored?
-      if attr = git_attributes['linguist-vendored']
-        return boolean_attribute(attr)
+      if not git_attributes['linguist-vendored'].nil?
+        boolean_attribute(git_attributes['linguist-vendored'])
       else
         super
       end
@@ -72,8 +72,8 @@ def language
     end
 
     def detectable?
-      if attr = git_attributes['linguist-detectable']
-        return boolean_attribute(attr)
+      if not git_attributes['linguist-detectable'].nil?
+        boolean_attribute(git_attributes['linguist-detectable'])
       else
         nil
       end
@@ -100,9 +100,9 @@ def cleanup!
 
     protected
 
-    # Returns true if the attribute is present and not the string "false".
+    # Returns true if the attribute is present and not the string "false" and not the false boolean.
     def boolean_attribute(attribute)
-      attribute != "false"
+      attribute != "false" && attribute != false
     end
 
     def load_blob!
diff --git a/test/test_repository.rb b/test/test_repository.rb
index a9862c11d5..c43d31a3d9 100644
--- a/test/test_repository.rb
+++ b/test/test_repository.rb
@@ -55,6 +55,14 @@ def test_repo_git_attributes
     # test/*.rb linguist-language=Java
     # Rakefile linguist-generated
     # test/fixtures/* linguist-vendored=false
+    # README.md linguist-documentation=false
+    # samples/Arduino/* linguist-documentation
+    # samples/Markdown/*.md linguist-detectable=true
+    # samples/HTML/*.html linguist-detectable=false
+    # samples/CSS/bootstrap.css -linguist-vendored
+    # samples/CSS/bootstrap.min.css -linguist-generated
+    # LICENSE -linguist-documentation
+    # samples/CoffeeScript/browser.coffee -linguist-detectable
 
     attr_commit = 'c20ebee0ebf33f73313d4694680521f80635d477'
     repo = linguist_repo(attr_commit)
@@ -96,47 +104,58 @@ def test_linguist_override_vendored?
   end
 
   def test_linguist_override_unvendored?
-    attr_commit = 'c20ebee0ebf33f73313d4694680521f80635d477'
+    attr_commit = '933c687cb8c02035394979b2308e5120a9904fdf'
     linguist_repo(attr_commit).read_index
 
     # lib/linguist/vendor.yml defines this as vendored.
     override_unvendored = Linguist::LazyBlob.new(rugged_repository, attr_commit, 'test/fixtures/foo.rb')
+    # test -linguist-vendored attribute method
+    override_unvendored_minus = Linguist::LazyBlob.new(rugged_repository, attr_commit, 'samples/CSS/bootstrap.css')
 
     # overridden .gitattributes
-    assert !override_unvendored.vendored?
+    refute override_unvendored.vendored?
+    refute override_unvendored_minus.vendored?
   end
 
   def test_linguist_override_documentation?
-    attr_commit = "d4c8fb8a28e91f97a7e53428a365c0abbac36d3d"
+    attr_commit = "933c687cb8c02035394979b2308e5120a9904fdf"
     linguist_repo(attr_commit).read_index
 
     readme = Linguist::LazyBlob.new(rugged_repository, attr_commit, "README.md")
     arduino = Linguist::LazyBlob.new(rugged_repository, attr_commit, "samples/Arduino/hello.ino")
+    # test -linguist-documentation attribute method
+    minus = Linguist::LazyBlob.new(rugged_repository, attr_commit, "LICENSE")
 
     # overridden by .gitattributes
     refute_predicate readme, :documentation?
     assert_predicate arduino, :documentation?
+    refute_predicate minus, :documentation?
   end
 
   def test_linguist_override_generated?
-    attr_commit = "c20ebee0ebf33f73313d4694680521f80635d477"
+    attr_commit = "933c687cb8c02035394979b2308e5120a9904fdf"
     linguist_repo(attr_commit).read_index
 
     rakefile = Linguist::LazyBlob.new(rugged_repository, attr_commit, "Rakefile")
-
+    # test  -linguist-generated attribute method
+    minus = Linguist::LazyBlob.new(rugged_repository, attr_commit, "samples/CSS/bootstrap.min.css")
     # overridden .gitattributes
     assert rakefile.generated?
+    refute minus.generated?
   end
 
   def test_linguist_override_detectable?
-    attr_commit = "8f86998866f6f2c8aa14e0dd430e61fd25cff720"
+    attr_commit = "933c687cb8c02035394979b2308e5120a9904fdf"
     linguist_repo(attr_commit).read_index
 
     # markdown is overridden by .gitattributes to be detectable, html to not be detectable
     markdown = Linguist::LazyBlob.new(rugged_repository, attr_commit, "samples/Markdown/tender.md")
     html = Linguist::LazyBlob.new(rugged_repository, attr_commit, "samples/HTML/pages.html")
+    # test  -linguist-detectable attribute method
+    minus = Linguist::LazyBlob.new(rugged_repository, attr_commit, "samples/CoffeeScript/browser.coffee")
 
     assert_predicate markdown, :detectable?
     refute_predicate html, :detectable?
+    refute_predicate minus, :detectable?
   end
 end