diff --git a/pkgs/racket-test-core/tests/racket/ffi-lock.rkt b/pkgs/racket-test-core/tests/racket/ffi-lock.rkt
new file mode 100644
index 0000000000..56acaa950f
--- /dev/null
+++ b/pkgs/racket-test-core/tests/racket/ffi-lock.rkt
@@ -0,0 +1,26 @@
+#lang racket
+(require ffi/unsafe)
+
+(define (go)
+  (place pch (s)))
+
+(define (s)
+  (define sleep (get-ffi-obj 'sleep #f (_fun #:lock-name "sleep-lock" _int -> _void)))
+  (printf "start\n")
+  (sleep 1)
+  (printf "done\n"))
+
+(module+ test
+  (when (memq (system-type) '(unix macosx))
+    (place-wait (go))
+    ;; Trigger a GC in space of place-shared objects:
+    (for ([i 1000])
+      (place-channel))
+    (define now (current-seconds))
+    (define l
+      (for/list ([i 3])
+        (go)))
+    (map place-wait l)
+    (unless ((- (current-seconds) now) . >= . 3)
+      (error "didn't serialize"))))
+
diff --git a/racket/src/foreign/foreign.c b/racket/src/foreign/foreign.c
index f1960f6b96..4cc23636b5 100644
--- a/racket/src/foreign/foreign.c
+++ b/racket/src/foreign/foreign.c
@@ -3221,6 +3221,16 @@ static Scheme_Object *make_vector_in_master(int count, Scheme_Object *val) {
   GC_switch_back_from_master(original_gc);
   return vec;
 }
+
+static void **malloc_immobile_box_in_master(Scheme_Object *v)
+{
+  void **imm;
+  void *original_gc;
+  original_gc = GC_switch_to_master_gc();
+  imm = scheme_malloc_immobile_box(v);
+  GC_switch_back_from_master(original_gc);
+  return imm;
+}
 #endif
 
 static void *name_to_ffi_lock(Scheme_Object *bstr)
@@ -3247,7 +3257,7 @@ static void *name_to_ffi_lock(Scheme_Object *bstr)
       lock = scheme_place_make_async_channel();
       lock = make_vector_in_master(2, lock);
       SCHEME_VEC_ELS(lock)[1] = scheme_make_integer(-1);
-      lock_box = scheme_malloc_immobile_box(lock);
+      lock_box = malloc_immobile_box_in_master(lock);
       old_lock_box = scheme_register_process_global(SCHEME_BYTE_STR_VAL(bstr), lock_box);
       if (old_lock_box) {
         scheme_free_immobile_box(lock_box);
diff --git a/racket/src/foreign/foreign.rktc b/racket/src/foreign/foreign.rktc
index ae5aa63868..dbd6145ed4 100755
--- a/racket/src/foreign/foreign.rktc
+++ b/racket/src/foreign/foreign.rktc
@@ -2386,6 +2386,16 @@ static Scheme_Object *make_vector_in_master(int count, Scheme_Object *val) {
   GC_switch_back_from_master(original_gc);
   return vec;
 }
+
+static void **malloc_immobile_box_in_master(Scheme_Object *v)
+{
+  void **imm;
+  void *original_gc;
+  original_gc = GC_switch_to_master_gc();
+  imm = scheme_malloc_immobile_box(v);
+  GC_switch_back_from_master(original_gc);
+  return imm;
+}
 #endif
 
 static void *name_to_ffi_lock(Scheme_Object *bstr)
@@ -2412,7 +2422,7 @@ static void *name_to_ffi_lock(Scheme_Object *bstr)
         lock = scheme_place_make_async_channel();
         lock = make_vector_in_master(2, lock);
         SCHEME_VEC_ELS(lock)[1] = scheme_make_integer(-1);
-        lock_box = scheme_malloc_immobile_box(lock);
+        lock_box = malloc_immobile_box_in_master(lock);
         old_lock_box = scheme_register_process_global(SCHEME_BYTE_STR_VAL(bstr), lock_box);
         if (old_lock_box) {
           scheme_free_immobile_box(lock_box);