chunker.patch

diff --git a/chunker.go b/chunker.go
index 593be8f..5632498 100644
--- a/chunker.go
+++ b/chunker.go
@@ -2,6 +2,7 @@ package chunker
 
 import (
        "errors"
+       "fmt"
        "io"
        "sync"
 )
@@ -265,6 +266,10 @@ func (c *Chunker) Next(data []byte) (Chunk, error) {
                                return Chunk{}, err
                        }
 
+                       if n < 0 {
+                               return Chunk{}, fmt.Errorf("ReadFull returned negative number of bytes read: %v", n)
+                       }
+
                        c.bpos = 0
                        c.bmax = uint(n)
                }