1 files changed, 8 insertions, 0 deletions
diff --git a/Library/Formula/mafft.rb b/Library/Formula/mafft.rb
index 69e6b3e5d..c16dd6e52 100644
--- a/Library/Formula/mafft.rb
+++ b/Library/Formula/mafft.rb
@@ -5,6 +5,14 @@ class Mafft < Formula
   url 'http://align.bmr.kyushu-u.ac.jp/mafft/software/mafft-6.717-with-extensions-src.tgz'
   sha1 '18d82340918949bbcdce659d4a09421ce06d67b1'
 
+  fails_with :clang do
+    build 421
+    cause <<-EOS.undent
+      Clang does not allow default arguments in out-of-line definitions of
+      class template members.
+      EOS
+  end
+
   def install
     cd 'core' do
       system "make", "CC=#{ENV.cc}",