diff --git a/core/blockchain_diff_test.go b/core/blockchain_diff_test.go
index 0b289bdc1c..d2d22bef6e 100644
--- a/core/blockchain_diff_test.go
+++ b/core/blockchain_diff_test.go
@@ -282,8 +282,9 @@ func TestFreezeDiffLayer(t *testing.T) {
 	defer fullBackend.close()
 	// Minus one empty block.
 	if fullBackend.chain.diffQueue.Size() != blockNum-1 {
-		t.Errorf("size of diff queue is wrong, expected: %d, get: %d", blockNum, fullBackend.chain.diffQueue.Size())
+		t.Errorf("size of diff queue is wrong, expected: %d, get: %d", blockNum-1, fullBackend.chain.diffQueue.Size())
 	}
+
 	time.Sleep(diffLayerFreezerRecheckInterval + 1*time.Second)
 	if fullBackend.chain.diffQueue.Size() != int(fullBackend.chain.triesInMemory) {
 		t.Errorf("size of diff queue is wrong, expected: %d, get: %d", blockNum, fullBackend.chain.diffQueue.Size())