diff --git a/tsdb/engine/tsm1/reader.go b/tsdb/engine/tsm1/reader.go
index 4ece9c8fbd..316cdbd6c2 100644
--- a/tsdb/engine/tsm1/reader.go
+++ b/tsdb/engine/tsm1/reader.go
@@ -697,7 +697,7 @@ func (f *fileAccessor) readBlock(entry *IndexEntry, values []Value) ([]Value, er
 	}
 
 	//TODO: Validate checksum
-	values, err = DecodeBlock(b[4:], values)
+	values, err = DecodeBlock(b, values)
 	if err != nil {
 		return nil, err
 	}
@@ -727,7 +727,7 @@ func (f *fileAccessor) readBytes(entry *IndexEntry, b []byte) ([]byte, error) {
 		return nil, err
 	}
 
-	return b[:n], nil
+	return b[4:n], nil
 }
 
 // ReadAll returns all values for a key in all blocks.
@@ -751,7 +751,7 @@ func (f *fileAccessor) readAll(key string) ([]Value, error) {
 
 		//TODO: Validate checksum
 		temp = temp[:0]
-		temp, err = DecodeBlock(b[4:], temp)
+		temp, err = DecodeBlock(b, temp)
 		if err != nil {
 			return nil, err
 		}
@@ -860,7 +860,7 @@ func (m *mmapAccessor) readBytes(entry *IndexEntry, b []byte) ([]byte, error) {
 		return nil, ErrTSMClosed
 	}
 
-	return m.b[entry.Offset : entry.Offset+int64(entry.Size)], nil
+	return m.b[entry.Offset+4 : entry.Offset+int64(entry.Size)], nil
 }
 
 // ReadAll returns all values for a key in all blocks.
diff --git a/tsdb/engine/tsm1/writer.go b/tsdb/engine/tsm1/writer.go
index 4df0e1159b..0f228848cc 100644
--- a/tsdb/engine/tsm1/writer.go
+++ b/tsdb/engine/tsm1/writer.go
@@ -518,12 +518,14 @@ func (t *tsmWriter) WriteBlock(key string, minTime, maxTime time.Time, block []b
 		}
 	}
 
-	n, err := t.w.Write(block)
+	checksum := crc32.ChecksumIEEE(block)
+
+	n, err := t.w.Write(append(u32tob(checksum), block...))
 	if err != nil {
 		return err
 	}
 
-	blockType, err := BlockType(block[4:])
+	blockType, err := BlockType(block)
 	if err != nil {
 		return err
 	}