diff --git a/src/lib.rs b/src/lib.rs
index 7af1dc9..4731b9a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -3,7 +3,7 @@ use indicatif::ProgressBarIter;
 use png;
 use pyo3::exceptions::PyValueError;
 use pyo3::prelude::*;
-use std::fs::File;
+use std::fs::{File, OpenOptions};
 use std::io::BufWriter;
 use std::path::Path;
 
@@ -72,7 +72,11 @@ impl Iterator for PacketsIterator {
 
 impl PacketsIterator {
     fn new(filename: &str) -> anyhow::Result<Self> {
-        let file = File::open(filename)?;
+        let file = OpenOptions::new()
+            .read(true)
+            .write(false)
+            .create(false)
+            .open(filename)?;
         let pb = ProgressBar::new(file.metadata()?.len());
         let wrap = pb.wrap_read(file);
         let cap = PcapNGReader::new(65535, wrap)?;
@@ -121,6 +125,7 @@ impl Header {
 const HDR_SIZE: usize = std::mem::size_of::<Header>();
 
 pub struct Frame {
+    #[allow(dead_code)]
     header: Header,
     raw: Vec<u8>,
 }