diff --git a/ext/concurrent-ruby-ext/atomic_boolean.c b/ext/concurrent-ruby-ext/atomic_boolean.c
index 78ce350f..7a94583f 100644
--- a/ext/concurrent-ruby-ext/atomic_boolean.c
+++ b/ext/concurrent-ruby-ext/atomic_boolean.c
@@ -2,7 +2,6 @@
 
 #include "atomic_boolean.h"
 #include "atomic_reference.h"
-#include "ruby_193_compatible.h"
 
 void atomic_boolean_mark(void *value) {
   rb_gc_mark_maybe((VALUE) value);
diff --git a/ext/concurrent-ruby-ext/atomic_fixnum.c b/ext/concurrent-ruby-ext/atomic_fixnum.c
index c40ae90b..d178c7ea 100644
--- a/ext/concurrent-ruby-ext/atomic_fixnum.c
+++ b/ext/concurrent-ruby-ext/atomic_fixnum.c
@@ -2,7 +2,6 @@
 
 #include "atomic_fixnum.h"
 #include "atomic_reference.h"
-#include "ruby_193_compatible.h"
 
 void atomic_fixnum_mark(void *value) {
   rb_gc_mark_maybe((VALUE) value);
diff --git a/ext/concurrent-ruby-ext/ruby_193_compatible.h b/ext/concurrent-ruby-ext/ruby_193_compatible.h
deleted file mode 100644
index d9531572..00000000
--- a/ext/concurrent-ruby-ext/ruby_193_compatible.h
+++ /dev/null
@@ -1,28 +0,0 @@
-#ifndef rb_check_arity
-
-// https://github.com/ruby/ruby/blob/ruby_2_0_0/include/ruby/intern.h
-// rb_check_arity was added in Ruby 2.0
-
-#define UNLIMITED_ARGUMENTS (-1)
-
-static inline VALUE rb_error_arity(int argc, int min, int max)
-{
-  VALUE err_mess = 0;
-  if (min == max) {
-    err_mess = rb_sprintf("wrong number of arguments (%d for %d)", argc, min);
-  }
-  else if (max == UNLIMITED_ARGUMENTS) {
-    err_mess = rb_sprintf("wrong number of arguments (%d for %d+)", argc, min);
-  }
-  else {
-    err_mess = rb_sprintf("wrong number of arguments (%d for %d..%d)", argc, min, max);
-  }
-  return rb_exc_new3(rb_eTypeError, err_mess);
-}
-
-#define rb_check_arity(argc, min, max) do { \
-  if (((argc) < (min)) || ((argc) > (max) && (max) != UNLIMITED_ARGUMENTS)) \
-  rb_exc_raise(rb_error_arity(argc, min, max)); \
-} while(0)
-
-#endif