diff --git a/tsdb/head_append.go b/tsdb/head_append.go
index 4a594f314..c6898c10c 100644
--- a/tsdb/head_append.go
+++ b/tsdb/head_append.go
@@ -940,7 +940,7 @@ func (a *headAppender) Commit() (err error) {
 					// !ok means there are no markers collected for these samples yet. So we first flush the samples
 					// before setting this m-map marker.
 
-					// r != 0 means we have already m-mapped a chunk for this series in the same Commit().
+					// r != nil means we have already m-mapped a chunk for this series in the same Commit().
 					// Hence, before we m-map again, we should add the samples and m-map markers
 					// seen till now to the WBL records.
 					collectOOORecords()
diff --git a/tsdb/ooo_head_read.go b/tsdb/ooo_head_read.go
index aedda49dd..14d3724e8 100644
--- a/tsdb/ooo_head_read.go
+++ b/tsdb/ooo_head_read.go
@@ -118,8 +118,8 @@ func (oh *OOOHeadIndexReader) series(ref storage.SeriesRef, builder *labels.Scra
 					addChunk(c.minTime, c.maxTime, ref, chk.chunk)
 				}
 			} else {
-				var enc chunkenc.Chunk
-				addChunk(c.minTime, c.maxTime, ref, enc)
+				var emptyChunk chunkenc.Chunk
+				addChunk(c.minTime, c.maxTime, ref, emptyChunk)
 			}
 		}
 	}