diff --git a/gc.c b/gc.c
index 4eaceef80714a5..0309559481b3b7 100644
--- a/gc.c
+++ b/gc.c
@@ -2204,13 +2204,14 @@ heap_prepare(rb_objspace_t *objspace, rb_size_pool_t *size_pool, rb_heap_t *heap
 {
     GC_ASSERT(heap->free_pages == NULL);
 
-    if (is_lazy_sweeping(objspace)) {
-	gc_sweep_continue(objspace, size_pool, heap);
-    }
-    else if (is_incremental_marking(objspace)) {
+    if (is_incremental_marking(objspace)) {
 	gc_marks_continue(objspace, size_pool, heap);
     }
 
+    if (heap->free_pages == NULL && is_lazy_sweeping(objspace)) {
+        gc_sweep_continue(objspace, size_pool, heap);
+    }
+
     if (heap->free_pages == NULL &&
         (will_be_incremental_marking(objspace) || heap_increment(objspace, size_pool, heap) == FALSE) &&
 	gc_start(objspace, GPR_FLAG_NEWOBJ) == FALSE) {