diff --git a/Library/Homebrew/macos.rb b/Library/Homebrew/macos.rb
index 147676b3c2..c56919949b 100644
--- a/Library/Homebrew/macos.rb
+++ b/Library/Homebrew/macos.rb
@@ -40,7 +40,13 @@ module MacOS extend self
   end
 
   def dev_tools_path
-    @dev_tools_path ||= if File.exist? "/usr/bin/cc" and File.exist? "/usr/bin/make"
+    @dev_tools_path ||= \
+    if File.exist? MacOS::CLT::STANDALONE_PKG_PATH and
+       File.exist? "#{MacOS::CLT::STANDALONE_PKG_PATH}/usr/bin/cc" and
+       File.exist? "#{MacOS::CLT::STANDALONE_PKG_PATH}/usr/bin/make"
+      # In 10.9 the CLT moved from /usr into /Library/Developer/CommandLineTools.
+      Pathname.new "#{MacOS::CLT::STANDALONE_PKG_PATH}/usr/bin"
+    elsif File.exist? "/usr/bin/cc" and File.exist? "/usr/bin/make"
       # probably a safe enough assumption (the unix way)
       Pathname.new "/usr/bin"
     # Note that the exit status of system "xcrun foo" isn't always accurate
diff --git a/Library/Homebrew/os/mac/xcode.rb b/Library/Homebrew/os/mac/xcode.rb
index 3fa7d62aea..202567eb4d 100644
--- a/Library/Homebrew/os/mac/xcode.rb
+++ b/Library/Homebrew/os/mac/xcode.rb
@@ -154,16 +154,16 @@ end
 module MacOS::CLT extend self
   STANDALONE_PKG_ID = "com.apple.pkg.DeveloperToolsCLILeo"
   FROM_XCODE_PKG_ID = "com.apple.pkg.DeveloperToolsCLI"
+  STANDALONE_PKG_PATH = Pathname.new("/Library/Developer/CommandLineTools")
 
-  # This is true ift he standard UNIX tools are present under /usr. For
-  # Xcode < 4.3, this is the standard location. Otherwise, it means that
-  # the user has installed the "Command Line Tools for Xcode" package.
-  # TODO: handle 10.9 CLT which has headers under:
-  # /Library/Developer/CommandLineTools/usr/include
+  # This is true if the standard UNIX tools are present in the expected location. For
+  # Mavericks and above this is /Library/Developer/CommandLineTools otherwise it is /usr.
+  # For Xcode < 4.3, this is the standard location. Otherwise, it means that the user has
+  # installed the "Command Line Tools for Xcode" package.
   def installed?
-    return false if MacOS.version > :mountain_lion
-    MacOS.dev_tools_path == Pathname.new("/usr/bin") and
-      File.directory? "/usr/include"
+    (MacOS.dev_tools_path == Pathname.new("#{MacOS::CLT::STANDALONE_PKG_PATH}/usr/bin") \
+      and File.directory? "#{MacOS::CLT::STANDALONE_PKG_PATH}/usr/include") or
+    (MacOS.dev_tools_path == Pathname.new("/usr/bin") and File.directory? "/usr/include")
   end
 
   def latest_version?