1 files changed, 1 insertions, 0 deletions
diff --git a/obj_map.c b/obj_map.c
index 9fdeb0af..d332254e 100644
--- a/obj_map.c
+++ b/obj_map.c
@@ -35,6 +35,7 @@ GC_API void GC_CALL GC_register_displacement(size_t offset)
 
 GC_INNER void GC_register_displacement_inner(size_t offset)
 {
+    GC_ASSERT(I_HOLD_LOCK());
     if (offset >= VALID_OFFSET_SZ) {
         ABORT("Bad argument to GC_register_displacement");
     }