diff --git a/Library/Homebrew/dependency.rb b/Library/Homebrew/dependency.rb
index d87d74ccf8..cc378b7dfc 100644
--- a/Library/Homebrew/dependency.rb
+++ b/Library/Homebrew/dependency.rb
@@ -20,7 +20,7 @@ class Dependency
   end
 
   def eql?(other)
-    other.is_a?(self.class) && hash == other.hash
+    instance_of?(other.class) && hash == other.hash
   end
 
   def hash