diff --git a/tsdb/chunkenc/bstream.go b/tsdb/chunkenc/bstream.go
index ad8077c27..c8efeab1d 100644
--- a/tsdb/chunkenc/bstream.go
+++ b/tsdb/chunkenc/bstream.go
@@ -95,7 +95,7 @@ func (b *bstream) writeByte(byt byte) {
 }
 
 func (b *bstream) writeBits(u uint64, nbits int) {
-	u <<= (64 - uint(nbits))
+	u <<= 64 - uint(nbits)
 	for nbits >= 8 {
 		byt := byte(u >> 56)
 		b.writeByte(byt)
diff --git a/tsdb/chunks/head_chunks.go b/tsdb/chunks/head_chunks.go
index bc6915c80..1443e0bd4 100644
--- a/tsdb/chunks/head_chunks.go
+++ b/tsdb/chunks/head_chunks.go
@@ -386,7 +386,7 @@ func (cdm *ChunkDiskMapper) cut() (returnErr error) {
 		cdm.readPathMtx.Unlock()
 	}
 
-	mmapFile, err := fileutil.OpenMmapFileWithSize(newFile.Name(), int(MaxHeadChunkFileSize))
+	mmapFile, err := fileutil.OpenMmapFileWithSize(newFile.Name(), MaxHeadChunkFileSize)
 	if err != nil {
 		return err
 	}