diff --git a/tsdb/compact.go b/tsdb/compact.go
index 6063e4a5f1..7c721de3ee 100644
--- a/tsdb/compact.go
+++ b/tsdb/compact.go
@@ -1176,13 +1176,17 @@ func (c *LeveledCompactor) populateSymbols(sets []storage.ChunkSeriesSet, outBlo
 			obIx = labels.StableHash(s.Labels()) % uint64(len(outBlocks))
 		}
 
-		for _, l := range s.Labels() {
+		err := s.Labels().Validate(func(l labels.Label) error {
 			if err := batchers[obIx].addSymbol(l.Name); err != nil {
 				return errors.Wrap(err, "addSymbol to batcher")
 			}
 			if err := batchers[obIx].addSymbol(l.Value); err != nil {
 				return errors.Wrap(err, "addSymbol to batcher")
 			}
+			return nil
+		})
+		if err != nil {
+			return err
 		}
 	}
 
diff --git a/tsdb/compact_test.go b/tsdb/compact_test.go
index f331adb675..4db5f3b178 100644
--- a/tsdb/compact_test.go
+++ b/tsdb/compact_test.go
@@ -596,10 +596,10 @@ func TestCompaction_CompactWithSplitting(t *testing.T) {
 						require.Equal(t, uint64(shardIndex), lbls.Labels().Hash()%shardCount)
 
 						// Collect all symbols used by series.
-						for _, l := range lbls.Labels() {
+						lbls.Labels().Range(func(l labels.Label) {
 							seriesSymbols[l.Name] = struct{}{}
 							seriesSymbols[l.Value] = struct{}{}
-						}
+						})
 					}
 					require.NoError(t, p.Err())