diff --git a/CHANGELOG.md b/CHANGELOG.md
index 65fb036f..b6d42490 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 ## master (unreleased)
 
 * Fix non-visible line number on light-colored terminal backgrounds
+* Allow files without `.haml` extension to be linted when explicitly specified
 
 ## 0.11.0
 
diff --git a/lib/haml_lint.rb b/lib/haml_lint.rb
index 217554d2..c22f13c1 100644
--- a/lib/haml_lint.rb
+++ b/lib/haml_lint.rb
@@ -11,6 +11,7 @@
 require 'haml_lint/logger'
 require 'haml_lint/reporter'
 require 'haml_lint/report'
+require 'haml_lint/file_finder'
 require 'haml_lint/runner'
 require 'haml_lint/utils'
 require 'haml_lint/version'
diff --git a/lib/haml_lint/file_finder.rb b/lib/haml_lint/file_finder.rb
new file mode 100644
index 00000000..78607efe
--- /dev/null
+++ b/lib/haml_lint/file_finder.rb
@@ -0,0 +1,69 @@
+require 'find'
+
+module HamlLint
+  # Finds HAML files that should be linted given a specified list of paths, glob
+  # patterns, and configuration.
+  class FileFinder
+    # List of extensions of files to include under a directory when a directory
+    # is specified instead of a file.
+    VALID_EXTENSIONS = %w[.haml]
+
+    # @param config [HamlLint::Configuration]
+    def initialize(config)
+      @config = config
+    end
+
+    # Return list of files to lint given the specified set of paths and glob
+    # patterns.
+    # @param patterns [Array<String>]
+    # @param excluded_patterns [Array<String>]
+    # @raise [HamlLint::Exceptions::InvalidFilePath]
+    # @return [Array<String>] list of actual files
+    def find(patterns, excluded_patterns)
+      extract_files_from(patterns).reject do |file|
+        excluded_patterns.any? do |exclusion_glob|
+          ::File.fnmatch?(exclusion_glob, file,
+                          ::File::FNM_PATHNAME | # Wildcards don't match path separators
+                          ::File::FNM_DOTMATCH)  # `*` wildcard matches dotfiles
+        end
+      end
+    end
+
+    private
+
+    def extract_files_from(patterns) # rubocop:disable MethodLength
+      files = []
+
+      patterns.each do |pattern|
+        if File.file?(pattern)
+          files << pattern
+        else
+          begin
+            ::Find.find(pattern) do |file|
+              files << file if haml_file?(file)
+            end
+          rescue ::Errno::ENOENT
+            # File didn't exist; it might be a file glob pattern
+            matches = ::Dir.glob(pattern)
+            if matches.any?
+              files += matches
+            else
+              # One of the paths specified does not exist; raise a more
+              # descriptive exception so we know which one
+              raise HamlLint::Exceptions::InvalidFilePath,
+                    "File path '#{pattern}' does not exist"
+            end
+          end
+        end
+      end
+
+      files.uniq
+    end
+
+    def haml_file?(file)
+      return false unless ::FileTest.file?(file)
+
+      VALID_EXTENSIONS.include?(::File.extname(file))
+    end
+  end
+end
diff --git a/lib/haml_lint/runner.rb b/lib/haml_lint/runner.rb
index 39a6f033..ec3401b7 100644
--- a/lib/haml_lint/runner.rb
+++ b/lib/haml_lint/runner.rb
@@ -9,7 +9,7 @@ class Runner
     # @return [HamlLint::Report] a summary of all lints found
     def run(options = {})
       config = load_applicable_config(options)
-      files = extract_applicable_files(options)
+      files = extract_applicable_files(options, config)
       linters = extract_enabled_linters(config, options)
 
       raise HamlLint::Exceptions::NoLintersError, 'No linters specified' if linters.empty?
@@ -63,16 +63,11 @@ def find_lints(file, linters, config)
       @lints << Lint.new(nil, file, ex.line, ex.to_s, :error)
     end
 
-    def extract_applicable_files(options)
+    def extract_applicable_files(options, config)
+      included_patterns = options[:files]
       excluded_files = options.fetch(:excluded_files, [])
 
-      Utils.extract_files_from(options[:files]).reject do |file|
-        excluded_files.any? do |exclusion_glob|
-          File.fnmatch?(exclusion_glob, file,
-                        File::FNM_PATHNAME | # Wildcards don't match path separators
-                        File::FNM_DOTMATCH)  # `*` wildcard matches dotfiles
-        end
-      end
+      HamlLint::FileFinder.new(config).find(included_patterns, excluded_files)
     end
   end
 end
diff --git a/lib/haml_lint/utils.rb b/lib/haml_lint/utils.rb
index c740b2a6..b1016191 100644
--- a/lib/haml_lint/utils.rb
+++ b/lib/haml_lint/utils.rb
@@ -1,35 +1,8 @@
-require 'find'
-
 module HamlLint
   # A miscellaneous set of utility functions.
   module Utils
     module_function
 
-    def extract_files_from(list)
-      files = []
-
-      list.each do |file|
-        begin
-          Find.find(file) do |f|
-            files << f if haml_file?(f)
-          end
-        rescue Errno::ENOENT
-          # File didn't exist; it might be a file glob pattern
-          matches = Dir.glob(file)
-          if matches.any?
-            files += matches
-          else
-            # One of the paths specified does not exist; raise a more
-            # descriptive exception so we know which one
-            raise HamlLint::Exceptions::InvalidFilePath,
-                  "File path '#{file}' does not exist"
-          end
-        end
-      end
-
-      files.uniq
-    end
-
     # Yields interpolated values within a block of filter text.
     def extract_interpolated_values(filter_text)
       Haml::Util.handle_interpolation(filter_text.dump) do |scan|
@@ -81,11 +54,5 @@ def count_consecutive(items, offset, satisfies)
       count += 1 while (offset + count < items.count) && satisfies[items[offset + count]]
       count
     end
-
-    def haml_file?(file)
-      return false unless FileTest.file?(file)
-
-      File.extname(file) == '.haml'
-    end
   end
 end
diff --git a/spec/haml_lint/file_finder_spec.rb b/spec/haml_lint/file_finder_spec.rb
new file mode 100644
index 00000000..6405fe76
--- /dev/null
+++ b/spec/haml_lint/file_finder_spec.rb
@@ -0,0 +1,101 @@
+require 'spec_helper'
+
+describe HamlLint::FileFinder do
+  let(:config) { double }
+  let(:excluded_patterns) { [] }
+
+  subject { described_class.new(config) }
+
+  describe '#find' do
+    include_context 'isolated environment'
+
+    subject { super().find(patterns, excluded_patterns) }
+
+    context 'when no patterns are given' do
+      let(:patterns) { [] }
+
+      context 'and there are no HAML files under the current directory' do
+        it { should == [] }
+      end
+
+      context 'and there are HAML files under the current directory' do
+        before do
+          `touch blah.haml`
+          `mkdir -p more`
+          `touch more/more.haml`
+        end
+
+        it { should == [] }
+      end
+    end
+
+    context 'when files without a valid extension are given' do
+      let(:patterns) { ['test.txt'] }
+
+      context 'and those files exist' do
+        before do
+          `touch test.txt`
+        end
+
+        it { should == ['test.txt'] }
+      end
+
+      context 'and those files do not exist' do
+        it 'raises an error' do
+          expect { subject }.to raise_error HamlLint::Exceptions::InvalidFilePath
+        end
+      end
+    end
+
+    context 'when directories are given' do
+      let(:patterns) { ['some-dir'] }
+
+      context 'and those directories exist' do
+        before do
+          `mkdir -p some-dir`
+        end
+
+        context 'and they contain HAML files' do
+          before do
+            `touch some-dir/test.haml`
+          end
+
+          it { should == ['some-dir/test.haml'] }
+        end
+
+        context 'and they contain more directories with files with recognized extensions' do
+          before do
+            `mkdir -p some-dir/more-dir`
+            `touch some-dir/more-dir/test.haml`
+          end
+
+          it { should == ['some-dir/more-dir/test.haml'] }
+        end
+
+        context 'and they contain files with some other extension' do
+          before do
+            `touch some-dir/test.txt`
+          end
+
+          it { should == [] }
+        end
+      end
+
+      context 'and those directories do not exist' do
+        it 'raises an error' do
+          expect { subject }.to raise_error HamlLint::Exceptions::InvalidFilePath
+        end
+      end
+    end
+
+    context 'when the same file is specified multiple times' do
+      let(:patterns) { ['test.haml'] * 3 }
+
+      before do
+        `touch test.haml`
+      end
+
+      it { should == ['test.haml'] }
+    end
+  end
+end
diff --git a/spec/support/isolated_environment.rb b/spec/support/isolated_environment.rb
new file mode 100644
index 00000000..934f5c01
--- /dev/null
+++ b/spec/support/isolated_environment.rb
@@ -0,0 +1,25 @@
+require 'fileutils'
+require 'tmpdir'
+
+shared_context 'isolated environment' do
+  around do |example|
+    Dir.mktmpdir do |tmpdir|
+      original_home = ENV['HOME']
+
+      begin
+        virtual_home = File.expand_path(File.join(tmpdir, 'home'))
+        Dir.mkdir(virtual_home)
+        ENV['HOME'] = virtual_home
+
+        working_dir = File.join(tmpdir, 'work')
+        Dir.mkdir(working_dir)
+
+        Dir.chdir(working_dir) do
+          example.run
+        end
+      ensure
+        ENV['HOME'] = original_home
+      end
+    end
+  end
+end