diff --git a/Library/Homebrew/unittest.rb b/Library/Homebrew/unittest.rb
index ba93e33ecd..ae8b0c1bc3 100755
--- a/Library/Homebrew/unittest.rb
+++ b/Library/Homebrew/unittest.rb
@@ -415,6 +415,15 @@ class BeerTasting <Test::Unit::TestCase
     assert_equal 10.7, f+0.1
   end
 
+  def test_arch_for_command
+    # NOTE only works on Snow Leopard I bet, pick a better file!
+    arches=arch_for_command '/usr/bin/svn'
+    assert_equal 3, arches.count
+    assert arches.include?(:x86_64)
+    assert arches.include?(:i386)
+    assert arches.include?(:ppc7400)
+  end
+
   def test_pathname_plus_yeast
     nostdout do
       assert_nothing_raised do
diff --git a/Library/Homebrew/utils.rb b/Library/Homebrew/utils.rb
index 7beaba8ad3..ff58aabfda 100644
--- a/Library/Homebrew/utils.rb
+++ b/Library/Homebrew/utils.rb
@@ -99,3 +99,24 @@ def exec_editor *args
   # we don't have to escape args, and escaping 100% is tricky
   exec *(editor.split+args)
 end
+
+# provide an absolute path to a command or this function will search the PATH
+def arch_for_command cmd
+    archs = []
+    cmd = `which #{cmd}` if not Pathname.new(cmd).absolute?
+
+    IO.popen("file #{cmd}").readlines.each do |line|
+      case line
+      when /Mach-O executable ppc/
+        archs << :ppc7400
+      when /Mach-O 64-bit executable ppc64/
+        archs << :ppc64
+      when /Mach-O executable i386/
+        archs << :i386
+      when /Mach-O 64-bit executable x86_64/
+        archs << :x86_64
+      end
+    end
+
+    return archs
+end