diff --git a/mars_trans_logger.c b/mars_trans_logger.c
index a4a34b14..2ea47b0d 100644
--- a/mars_trans_logger.c
+++ b/mars_trans_logger.c
@@ -659,31 +659,35 @@ int _write_ref_get(struct trans_logger_output *output, struct trans_logger_mref_
 static noinline
 int trans_logger_ref_get(struct trans_logger_output *output, struct mref_object *mref)
 {
-	struct trans_logger_brick *brick = output->brick;
+	struct trans_logger_brick *brick;
 	struct trans_logger_mref_aspect *mref_a;
 	loff_t base_offset;
 
 	CHECK_PTR(output, err);
+	brick = output->brick;
+	CHECK_PTR(brick, err);
+	CHECK_PTR(mref, err);
 
 	MARS_IO("pos = %lld len = %d\n", mref->ref_pos, mref->ref_len);
 
-	if (mref->ref_len > brick->max_mref_size && brick->max_mref_size > 0)
-		mref->ref_len = brick->max_mref_size;
+	mref_a = trans_logger_mref_get_aspect(brick, mref);
+	CHECK_PTR(mref_a, err);
+	CHECK_ASPECT(mref_a, mref, err);
 
 	atomic_inc(&brick->outer_balance_count);
 
-	if (atomic_read(&mref->ref_count) > 0) { // setup already performed
+	if (mref_a->stamp.tv_sec) { // setup already performed
 		MARS_IO("again %d\n", atomic_read(&mref->ref_count));
-		atomic_inc(&mref->ref_count);
+		CHECK_ATOMIC(&mref->ref_count, 1);
+		atomic_inc(&mref->ref_count); // must be paired with __trans_logger_ref_put()
 		return mref->ref_len;
 	}
 
-	mref_a = trans_logger_mref_get_aspect(brick, mref);
-	CHECK_PTR(mref_a, err);
-	CHECK_PTR(mref_a->object, err);
-
 	get_lamport(&mref_a->stamp);
 
+	if (mref->ref_len > brick->max_mref_size && brick->max_mref_size > 0)
+		mref->ref_len = brick->max_mref_size;
+
 	// ensure that REGION_SIZE boundaries are obeyed by hashing
 	base_offset = mref->ref_pos & (loff_t)(REGION_SIZE - 1);
 	if (mref->ref_len > REGION_SIZE - base_offset) {