diff --git a/tsdb/chunks/head_chunks_test.go b/tsdb/chunks/head_chunks_test.go
index 8ada3ecb5a..a80a1daab9 100644
--- a/tsdb/chunks/head_chunks_test.go
+++ b/tsdb/chunks/head_chunks_test.go
@@ -595,7 +595,7 @@ func writeUnsupportedChunk(t *testing.T, idx int, hrw *ChunkDiskMapper) (seriesR
 }
 
 const (
-	UnsupportedMask   = 0b11000000
+	UnsupportedMask   = 0b01000000
 	EncUnsupportedXOR = chunkenc.EncXOR | UnsupportedMask
 )