diff --git a/lib/fs/reader_at.go b/lib/fs/reader_at.go
index 0c5e6d7cc0..672a8d48df 100644
--- a/lib/fs/reader_at.go
+++ b/lib/fs/reader_at.go
@@ -90,7 +90,7 @@ func (r *ReaderAt) MustReadAt(p []byte, off int64) {
 }
 
 func (r *ReaderAt) isInPageCache(start, end int64) bool {
-	if int64(len(r.mmapData)) - end < 4096 {
+	if int64(len(r.mmapData))-end < 4096 {
 		// If standard copy(dst, src) from Go may read beyond len(src), then this should help
 		// fixing SIGBUS panic from https://github.com/VictoriaMetrics/VictoriaMetrics/issues/581
 		return false