diff --git a/bootstraptest/test_ractor.rb b/bootstraptest/test_ractor.rb
index 00ac1487c6..94c0635c72 100644
--- a/bootstraptest/test_ractor.rb
+++ b/bootstraptest/test_ractor.rb
@@ -2210,3 +2210,10 @@ assert_equal 'ok', %q{
   end
   'ok'
 }
+
+# fork after creating Ractor
+assert_equal 'ok', %q{
+  Ractor.new { Ractor.receive }
+  _, status = Process.waitpid2 fork { }
+  status.success? ? "ok" : status
+}
diff --git a/ractor.c b/ractor.c
index 1b66f2dda5..c536d27e4e 100644
--- a/ractor.c
+++ b/ractor.c
@@ -2072,6 +2072,8 @@ rb_ractor_main_alloc(void)
 }
 
 #if defined(HAVE_WORKING_FORK)
+// Set up the main Ractor for the VM after fork.
+// Puts us in "single Ractor mode"
 void
 rb_ractor_atfork(rb_vm_t *vm, rb_thread_t *th)
 {
@@ -2087,6 +2089,14 @@ rb_ractor_atfork(rb_vm_t *vm, rb_thread_t *th)
     VM_ASSERT(vm->ractor.blocking_cnt == 0);
     VM_ASSERT(vm->ractor.cnt == 1);
 }
+
+void
+rb_ractor_terminate_atfork(rb_vm_t *vm, rb_ractor_t *r)
+{
+    rb_gc_ractor_cache_free(r->newobj_cache);
+    r->newobj_cache = NULL;
+    r->status_ = ractor_terminated;
+}
 #endif
 
 void rb_thread_sched_init(struct rb_thread_sched *, bool atfork);
diff --git a/ractor_core.h b/ractor_core.h
index 1e860edb4b..51fb3246ac 100644
--- a/ractor_core.h
+++ b/ractor_core.h
@@ -223,6 +223,7 @@ void rb_ractor_terminate_interrupt_main_thread(rb_ractor_t *r);
 void rb_ractor_terminate_all(void);
 bool rb_ractor_main_p_(void);
 void rb_ractor_atfork(rb_vm_t *vm, rb_thread_t *th);
+void rb_ractor_terminate_atfork(rb_vm_t *vm, rb_ractor_t *th);
 VALUE rb_ractor_require(VALUE feature);
 VALUE rb_ractor_autoload_load(VALUE space, ID id);
 
diff --git a/thread.c b/thread.c
index d09767cb75..e56545e1c0 100644
--- a/thread.c
+++ b/thread.c
@@ -4740,6 +4740,9 @@ rb_thread_atfork_internal(rb_thread_t *th, void (*atfork)(rb_thread_t *, const r
 
     // OK. Only this thread accesses:
     ccan_list_for_each(&vm->ractor.set, r, vmlr_node) {
+        if (r != vm->ractor.main_ractor) {
+            rb_ractor_terminate_atfork(vm, r);
+        }
         ccan_list_for_each(&r->threads.set, i, lt_node) {
             atfork(i, th);
         }