diff --git a/.changesets/fix-t_data-warning-on-ruby-3-2.md b/.changesets/fix-t_data-warning-on-ruby-3-2.md
new file mode 100644
index 000000000..af58d7219
--- /dev/null
+++ b/.changesets/fix-t_data-warning-on-ruby-3-2.md
@@ -0,0 +1,6 @@
+---
+bump: "patch"
+type: "fix"
+---
+
+Fix the T_DATA warning originating from the AppSignal C extension on Ruby 3.2.
diff --git a/ext/appsignal_extension.c b/ext/appsignal_extension.c
index 7a91bb5b4..8e3f93dc2 100644
--- a/ext/appsignal_extension.c
+++ b/ext/appsignal_extension.c
@@ -845,9 +845,13 @@ static VALUE set_environment_metadata(VALUE self, VALUE key, VALUE value) {
 void Init_appsignal_extension(void) {
   Appsignal = rb_define_module("Appsignal");
   Extension = rb_define_class_under(Appsignal, "Extension", rb_cObject);
+  rb_undef_alloc_func(Extension);
   Transaction = rb_define_class_under(Extension, "Transaction", rb_cObject);
+  rb_undef_alloc_func(Transaction);
   Data = rb_define_class_under(Extension, "Data", rb_cObject);
+  rb_undef_alloc_func(Data);
   Span = rb_define_class_under(Extension, "Span", rb_cObject);
+  rb_undef_alloc_func(Span);
 
   // Starting and stopping
   rb_define_singleton_method(Extension, "start",    start,    0);