diff --git a/Library/Homebrew/cmd/install.rb b/Library/Homebrew/cmd/install.rb
index df98503073f35..935865bcced05 100644
--- a/Library/Homebrew/cmd/install.rb
+++ b/Library/Homebrew/cmd/install.rb
@@ -205,7 +205,7 @@ def install
 
   def check_ppc
     case Hardware::CPU.type
-    when :ppc, :dunno
+    when :ppc
       abort <<-EOS.undent
         Sorry, Homebrew does not support your computer's CPU architecture.
         For PPC support, see: https://github.com/mistydemeo/tigerbrew