diff --git a/lib/cocoa/objc/method_def.rb b/lib/cocoa/objc/method_def.rb
index c588790..21779ba 100644
--- a/lib/cocoa/objc/method_def.rb
+++ b/lib/cocoa/objc/method_def.rb
@@ -177,7 +177,7 @@ def ffi_casted values
         case value
         when TrueClass, FalseClass
           [:bool,value]
-        when Fixnum, Bignum
+        when Integer
           [TYPES[types[i]],value]
         when Float
           [:double,value]