diff --git a/app/vlselect/logsql/sort_writer.go b/app/vlselect/logsql/sort_writer.go
index dcb3b8893b..919fc8310b 100644
--- a/app/vlselect/logsql/sort_writer.go
+++ b/app/vlselect/logsql/sort_writer.go
@@ -7,6 +7,7 @@ import (
 	"sync"
 
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logjson"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logstorage"
 )
@@ -168,7 +169,9 @@ func (rs *rowsSorter) parseRows(src []byte) {
 			continue
 		}
 
-		p.ParseLogMessage(line)
+		if err := p.ParseLogMessage(line); err != nil {
+			logger.Panicf("BUG: unexpected invalid JSON line: %s", err)
+		}
 
 		timeValue := ""
 		fieldsBufLen := len(fieldsBuf)