diff --git a/src/appstate.rs b/src/appstate.rs
index 979f03f..e253e53 100644
--- a/src/appstate.rs
+++ b/src/appstate.rs
@@ -8,19 +8,15 @@ use console::style;
 use indicatif::{ProgressBar, ProgressStyle};
 use log::{debug, warn};
 
-use crate::file::Chunk;
-
 use super::{
     cachefile::CacheFile,
     cli::Cli,
-    file::{self, FileTrait},
+    file::{self, FileTrait, Chunk},
     sharry::{self, Client},
 };
 
 pub struct AppState {
     progress: RefCell<Option<ProgressBar>>,
-    buffer: Vec<u8>,
-
     http: ureq::Agent,
     inner: CacheFile,
 }
@@ -41,10 +37,9 @@ fn new_http(timeout: Option<Duration>) -> ureq::Agent {
 }
 
 impl AppState {
-    fn new(chunk_size: usize, http: ureq::Agent, inner: CacheFile) -> Self {
+    fn new(http: ureq::Agent, inner: CacheFile) -> Self {
         Self {
-            progress: None.into(),
-            buffer: vec![0; chunk_size * 1024 * 1024],
+            progress: RefCell::new(None),
             http,
             inner,
         }
@@ -55,11 +50,7 @@ impl AppState {
             .inspect_err(|e| debug!("could not resume from hash {:?}: {e}", args.get_hash()))
             .ok()?;
 
-        Some(Self::new(
-            args.chunk_size,
-            new_http(args.get_timeout()),
-            inner,
-        ))
+        Some(Self::new(new_http(args.get_timeout()), inner))
     }
 
     pub fn from_args(args: &Cli) -> sharry::Result<Self> {
@@ -71,11 +62,7 @@ impl AppState {
             args.get_share_request(),
         )?;
 
-        Ok(Self::new(
-            args.chunk_size,
-            http,
-            CacheFile::from_args(args, share_id),
-        ))
+        Ok(Self::new(http, CacheFile::from_args(args, share_id)))
     }
 
     fn get_or_create_progressbar(&self, uploading: &file::Uploading) -> Ref<'_, ProgressBar> {
@@ -114,7 +101,7 @@ impl AppState {
         }
     }
 
-    fn next_chunk(&mut self) -> io::Result<Option<Chunk>> {
+    fn next_chunk<'t>(&mut self, buffer: &'t mut [u8]) -> io::Result<Option<Chunk<'t>>> {
         let Some(mut uploading) = self.inner.pop_file(&self.http) else {
             self.inner
                 .share_notify(&self.http)
@@ -122,15 +109,14 @@ impl AppState {
 
             return Ok(None);
         };
-
         debug!("{uploading:?}");
 
         self.get_or_create_progressbar(&uploading);
 
-        let chunk = uploading.read(&mut self.buffer);
+        let chunk_res = uploading.read(buffer);
         self.inner.push_file(uploading);
-        let chunk = chunk?;
 
+        let chunk = chunk_res?;
         debug!("{chunk:?}");
 
         Ok(Some(chunk))
@@ -146,7 +132,7 @@ impl AppState {
                 let bar = self.get_or_create_progressbar(&uploading);
                 bar.set_position(uploading.get_offset());
                 // BUG in `indicatif` crate?
-                // `set_position` does not force immediate redraw, so we also call `inc_length` here
+                // `set_position` does not force an immediate redraw, so we also call `inc_length` here
                 bar.inc_length(0);
                 drop(bar);
 
@@ -161,8 +147,8 @@ impl AppState {
         self.inner.is_empty()
     }
 
-    pub fn upload_chunk(&mut self) -> sharry::Result<bool> {
-        let Some(chunk) = self.next_chunk()? else {
+    pub fn upload_chunk(&mut self, buffer: &mut [u8]) -> sharry::Result<bool> {
+        let Some(chunk) = self.next_chunk(buffer)? else {
             return Ok(true);
         };
 
@@ -170,7 +156,7 @@ impl AppState {
             chunk.get_patch_uri(),
             self.inner.alias_id(),
             chunk.get_offset(),
-            unsafe { chunk.get_data() },
+            chunk.get_data(),
         )?;
 
         Ok(self.is_done())
diff --git a/src/file/chunk.rs b/src/file/chunk.rs
index 8cf3c49..f93f172 100644
--- a/src/file/chunk.rs
+++ b/src/file/chunk.rs
@@ -1,25 +1,23 @@
 use std::fmt;
 
-pub struct Chunk {
-    data: *const [u8],
+pub struct Chunk<'t> {
+    data: &'t [u8],
     patch_uri: String,
     offset: u64,
 }
 
-impl fmt::Debug for Chunk {
+impl fmt::Debug for Chunk<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("Chunk")
             .field("patch_uri", &self.patch_uri)
             .field("offset", &self.offset)
-            .field("data_len", &self.data.len())
+            .field("data.len()", &self.data.len())
             .finish_non_exhaustive()
     }
 }
 
-impl Chunk {
-    pub fn new(data: &[u8], patch_uri: String, offset: u64) -> Self {
-        let data: *const [u8] = data as *const [u8];
-
+impl<'t> Chunk<'t> {
+    pub fn new(data: &'t [u8], patch_uri: String, offset: u64) -> Self {
         Self {
             data,
             patch_uri,
@@ -27,8 +25,8 @@ impl Chunk {
         }
     }
 
-    pub unsafe fn get_data(&self) -> &[u8] {
-        unsafe { &*self.data }
+    pub fn get_data(&self) -> &[u8] {
+        self.data
     }
 
     pub fn get_length(&self) -> u64 {
diff --git a/src/file/uploading.rs b/src/file/uploading.rs
index 2831bcd..dc40d86 100644
--- a/src/file/uploading.rs
+++ b/src/file/uploading.rs
@@ -52,7 +52,7 @@ impl Uploading {
         })
     }
 
-    pub fn read(&mut self, buf: &mut [u8]) -> io::Result<Chunk> {
+    pub fn read<'t>(&mut self, buf: &'t mut [u8]) -> io::Result<Chunk<'t>> {
         let mut f = fs::File::open(&self.path)?;
 
         f.seek(SeekFrom::Start(self.offset))?;
diff --git a/src/main.rs b/src/main.rs
index 38b799d..9477a8a 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -113,8 +113,10 @@ fn main() {
         style(state.file_names().join(", ")).magenta(),
     );
 
+    let mut buffer = vec![0; args.chunk_size * 1024 * 1024];
+
     loop {
-        match state.upload_chunk() {
+        match state.upload_chunk(&mut buffer) {
             Err(e) => error!("error: {e:?}"), // HACK handle errors better
             Ok(true) => {
                 info!("all uploads done");