diff --git a/server/torr/storage/torrstor/reader.go b/server/torr/storage/torrstor/reader.go
index 28be26f..c659b6b 100644
--- a/server/torr/storage/torrstor/reader.go
+++ b/server/torr/storage/torrstor/reader.go
@@ -90,6 +90,9 @@ func (r *Reader) Read(p []byte) (n int, err error) {
 }
 
 func (r *Reader) SetReadahead(length int64) {
+	if length > r.cache.capacity {
+		length = r.cache.capacity
+	}
 	r.Reader.SetReadahead(length)
 	r.readahead = length
 }