diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ee7f0ed..b322ea8 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -59,7 +59,6 @@ jobs:
 
         # macOS with venv
         - { os: macos-latest   , ruby: "3.3" , python: "3.x"  , python_architecture: x64 , venv: "venv:"  }
-        - { os: macos-latest   , ruby: "3.3" , python: "3.8"  , python_architecture: x64 , venv: "venv:"  }
 
         #- { os: macos-latest   , ruby: debug , python: "3.x" , python_architecture: x64 , venv: "" }
 
diff --git a/ext/pycall/extconf.rb b/ext/pycall/extconf.rb
index 6405fe9..7dd1167 100644
--- a/ext/pycall/extconf.rb
+++ b/ext/pycall/extconf.rb
@@ -1,3 +1,5 @@
 require 'mkmf'
 
+have_func("RTYPEDDATA_GET_DATA")
+
 create_makefile('pycall')
diff --git a/ext/pycall/range.c b/ext/pycall/range.c
index 40fc0cc..c9d1e1c 100644
--- a/ext/pycall/range.c
+++ b/ext/pycall/range.c
@@ -6,6 +6,12 @@ struct enumerator_head {
     VALUE args;
 };
 
+#ifdef HAVE_RTYPEDDATA_GET_DATA
+# define GET_ENUMERATOR_DATA(obj) ((struct enumerator_head *)RTYPEDDATA_GET_DATA(obj))
+#else
+# define GET_ENUMERATOR_DATA(obj) ((struct enumerator_head *)DATA_PTR(obj))
+#endif
+
 int
 pycall_obj_is_step_range(VALUE obj)
 {
@@ -19,7 +25,7 @@ pycall_obj_is_step_range(VALUE obj)
     return 0;
   }
 
-  eh = (struct enumerator_head *)DATA_PTR(obj);
+  eh = GET_ENUMERATOR_DATA(obj);
 
   if (!rb_obj_is_kind_of(eh->obj, rb_cRange)) {
     return 0;
@@ -50,7 +56,7 @@ pycall_extract_range(VALUE obj, VALUE *pbegin, VALUE *pend, int *pexclude_end, V
     exclude_end = rb_funcallv(obj, id_exclude_end, 0, 0);
   }
   else if (pycall_obj_is_step_range(obj)) {
-    struct enumerator_head *eh = (struct enumerator_head *)DATA_PTR(obj);
+    struct enumerator_head *eh = GET_ENUMERATOR_DATA(obj);
     begin = rb_funcallv(eh->obj, id_begin, 0, 0);
     end   = rb_funcallv(eh->obj, id_end,   0, 0);
     exclude_end = rb_funcallv(eh->obj, id_exclude_end, 0, 0);