diff --git a/Library/Homebrew/cmd/command.rb b/Library/Homebrew/cmd/command.rb
index 4790a69524..ad7f99288e 100644
--- a/Library/Homebrew/cmd/command.rb
+++ b/Library/Homebrew/cmd/command.rb
@@ -4,9 +4,7 @@ module Homebrew
     cmd = ARGV.first
     cmd = HOMEBREW_INTERNAL_COMMAND_ALIASES.fetch(cmd, cmd)
 
-    if (path = HOMEBREW_LIBRARY_PATH/"cmd/#{cmd}.rb").file?
-      puts path
-    elsif ARGV.homebrew_developer? && (path = HOMEBREW_LIBRARY_PATH/"dev-cmd/#{cmd}.rb").file?
+    if (path = internal_command_path cmd)
       puts path
     elsif (path = which("brew-#{cmd}") || which("brew-#{cmd}.rb"))
       puts path
@@ -14,4 +12,17 @@ module Homebrew
       odie "Unknown command: #{cmd}"
     end
   end
+
+  private
+
+  def internal_command_path(cmd)
+    extensions = %w[rb sh]
+    paths = extensions.map { |ext| HOMEBREW_LIBRARY_PATH/"cmd/#{cmd}.#{ext}" }
+
+    if ARGV.homebrew_developer?
+      paths += extensions.map { |ext| HOMEBREW_LIBRARY_PATH/"dev-cmd/#{cmd}.#{ext}" }
+    end
+
+    paths.find { |p| p.file? }
+  end
 end
diff --git a/Library/Homebrew/test/test_commands.rb b/Library/Homebrew/test/test_commands.rb
index 0fb46dd9c5..78a5d1c287 100644
--- a/Library/Homebrew/test/test_commands.rb
+++ b/Library/Homebrew/test/test_commands.rb
@@ -1,8 +1,9 @@
 require "testing_env"
+require "cmd/command"
 require "cmd/commands"
 require "fileutils"
 
-class CommandsCommandTests < Homebrew::TestCase
+class CommandsTests < Homebrew::TestCase
   def setup
     @cmds = [
       # internal commands
@@ -59,4 +60,23 @@ class CommandsCommandTests < Homebrew::TestCase
   ensure
     ENV.replace(env)
   end
+
+  def test_internal_command_path
+    assert_equal HOMEBREW_LIBRARY_PATH/"cmd/rbcmd.rb",
+                 Homebrew.send(:internal_command_path, "rbcmd")
+    assert_equal HOMEBREW_LIBRARY_PATH/"cmd/shcmd.sh",
+                 Homebrew.send(:internal_command_path, "shcmd")
+    assert_nil Homebrew.send(:internal_command_path, "idontexist1234")
+  end
+
+  def test_internal_dev_command_path
+    ARGV.stubs(:homebrew_developer?).returns false
+    assert_nil Homebrew.send(:internal_command_path, "rbdevcmd")
+
+    ARGV.stubs(:homebrew_developer?).returns true
+    assert_equal HOMEBREW_LIBRARY_PATH/"dev-cmd/rbdevcmd.rb",
+                 Homebrew.send(:internal_command_path, "rbdevcmd")
+    assert_equal HOMEBREW_LIBRARY_PATH/"dev-cmd/shdevcmd.sh",
+                 Homebrew.send(:internal_command_path, "shdevcmd")
+  end
 end