diff --git a/Formula/aggregate.rb b/Formula/aggregate.rb
index 06b6b742fbbad..5e9e0a1115f8a 100644
--- a/Formula/aggregate.rb
+++ b/Formula/aggregate.rb
@@ -5,6 +5,8 @@ class Aggregate < Formula
   url 'ftp://ftp.isc.org/isc/aggregate/aggregate-1.6.tar.gz'
   sha1 '13420baf4f3f93dbed3c380ab6cca175609c5d7d'
 
+  conflicts_with 'crush-tools', :because => 'both install an `aggregate` binary'
+
   def install
     bin.mkpath
     man1.mkpath
diff --git a/Formula/crush-tools.rb b/Formula/crush-tools.rb
index 26e5df28e6a73..6af785cebf13e 100644
--- a/Formula/crush-tools.rb
+++ b/Formula/crush-tools.rb
@@ -8,6 +8,8 @@ class CrushTools < Formula
 
   depends_on 'pcre'
 
+  conflicts_with 'aggregate', :because => 'both install an `aggregate` binary'
+
   def install
     # find Homebrew's libpcre
     ENV.append 'LDFLAGS', "-L#{HOMEBREW_PREFIX}/lib"