diff --git a/lib/mutant/matcher/method.rb b/lib/mutant/matcher/method.rb
index 90a1dd1e..7289bf9b 100644
--- a/lib/mutant/matcher/method.rb
+++ b/lib/mutant/matcher/method.rb
@@ -18,7 +18,7 @@ module Mutant
 
       # Methods within rbx kernel directory are precompiled and their source 
       # cannot be accessed via reading source location
-      BLACKLIST = %r(\Akernel/).freeze
+      BLACKLIST = /\Akernel\//.freeze
 
       # Enumerate matches
       #