diff --git a/collects/tests/racket/place-master-gc.rkt b/collects/tests/racket/place-master-gc.rkt
new file mode 100644
index 0000000000..974425f52a
--- /dev/null
+++ b/collects/tests/racket/place-master-gc.rkt
@@ -0,0 +1,5 @@
+#lang racket/base
+
+;; Try to trigger master GCs:
+(for ([i 100000])
+  (make-shared-bytes 1024))
diff --git a/src/racket/src/env.c b/src/racket/src/env.c
index dfe7a8ba6c..60840f1339 100644
--- a/src/racket/src/env.c
+++ b/src/racket/src/env.c
@@ -292,6 +292,7 @@ Scheme_Env *scheme_engine_instance_init()
 #if defined(MZ_PRECISE_GC) && defined(MZ_USE_PLACES)
   {
     void *signal_handle;
+    REGISTER_SO(place_object);
     place_object = (Scheme_Place_Object*) scheme_make_place_object();
     signal_handle = scheme_get_signal_handle();
     GC_set_put_external_event_fd(signal_handle);
diff --git a/src/racket/src/place.c b/src/racket/src/place.c
index 96c10b2bf3..de3f85c5bf 100644
--- a/src/racket/src/place.c
+++ b/src/racket/src/place.c
@@ -2189,6 +2189,7 @@ static void *place_start_proc_after_stack(void *data_arg, void *stack_base) {
     channel = place_data->channel;
   }
   place_obj = place_data->place_obj;
+  REGISTER_SO(place_object);
   place_object = place_obj;
   place_obj->refcount++;