diff --git a/ruby-to-rust/src/main.rb b/ruby-to-rust/src/main.rb
index 146de37..0c0d7c8 100644
--- a/ruby-to-rust/src/main.rb
+++ b/ruby-to-rust/src/main.rb
@@ -1,14 +1,8 @@
 require 'ffi'
 
-if RUBY_PLATFORM.include?('darwin')
-  EXT = 'dylib'
-else
-  EXT = 'so'
-end
-
 module Hello
   extend FFI::Library
-  ffi_lib 'target/debug/libdouble_input.' + EXT
+  ffi_lib 'target/debug/libdouble_input.' + FFI::Platform::LIBSUFFIX
   attach_function :double_input, [ :int ], :int
 end