gistfile1.diff

diff --git a/kernel/common/module.rb b/kernel/common/module.rb
index dffe98a..5bb7501 100644
--- a/kernel/common/module.rb
+++ b/kernel/common/module.rb
@@ -168,25 +168,41 @@ class Module
   end
 
   def public_method_defined?(sym)
-    sym = Rubinius::Type.coerce_to_symbol(sym)
+    sym = sym.to_str if sym.respond_to?(:to_str)
+    unless Rubinius::Type.object_kind_of?(sym, String) || Rubinius::Type.object_kind_of?(sym, Symbol)
+      raise TypeError, "#{sym.inspect} is not a Symbol"
+    end
+
     mod, meth = lookup_method(sym, false)
     meth ? meth.public? : false
   end
 
   def private_method_defined?(sym)
-    sym = Rubinius::Type.coerce_to_symbol(sym)
+    sym = sym.to_str if sym.respond_to?(:to_str)
+    unless Rubinius::Type.object_kind_of?(sym, String) || Rubinius::Type.object_kind_of?(sym, Symbol)
+      raise TypeError, "#{sym.inspect} is not a Symbol"
+    end
+
     mod, meth = lookup_method(sym, false)
     meth ? meth.private? : false
   end
 
   def protected_method_defined?(sym)
-    sym = Rubinius::Type.coerce_to_symbol(sym)
+    sym = sym.to_str if sym.respond_to?(:to_str)
+    unless Rubinius::Type.object_kind_of?(sym, String) || Rubinius::Type.object_kind_of?(sym, Symbol)
+      raise TypeError, "#{sym.inspect} is not a Symbol"
+    end
+
     mod, meth = lookup_method(sym, false)
     meth ? meth.protected? : false
   end
 
   def method_defined?(sym)
-    sym = Rubinius::Type.coerce_to_symbol(sym)
+    sym = sym.to_str if sym.respond_to?(:to_str)
+    unless Rubinius::Type.object_kind_of?(sym, String) || Rubinius::Type.object_kind_of?(sym, Symbol)
+      raise TypeError, "#{sym.inspect} is not a Symbol"
+    end
+
     mod, meth = lookup_method(sym, false)
     meth ? meth.public? || meth.protected? : false
   end