diff --git a/src/tools/remote-test-client/src/main.rs b/src/tools/remote-test-client/src/main.rs
index bcda930d093c5..760da539a9e6b 100644
--- a/src/tools/remote-test-client/src/main.rs
+++ b/src/tools/remote-test-client/src/main.rs
@@ -300,7 +300,7 @@ fn run(support_lib_count: usize, exe: String, all_args: Vec<String>) {
 
     // Ok now it's time to read all the output. We're receiving "frames"
     // representing stdout/stderr, so we decode all that here.
-    let mut header = [0; 5];
+    let mut header = [0; 9];
     let mut stderr_done = false;
     let mut stdout_done = false;
     let mut client = t!(client.into_inner());
@@ -308,10 +308,10 @@ fn run(support_lib_count: usize, exe: String, all_args: Vec<String>) {
     let mut stderr = io::stderr();
     while !stdout_done || !stderr_done {
         t!(client.read_exact(&mut header));
-        let amt = ((header[1] as u64) << 24)
-            | ((header[2] as u64) << 16)
-            | ((header[3] as u64) << 8)
-            | ((header[4] as u64) << 0);
+        let mut amt = 0u64;
+        for (i, &byte) in header[1..=8].iter().enumerate() {
+            amt |= (byte as u64) << (56 - 8 * i);
+        }
         if header[0] == 0 {
             if amt == 0 {
                 stdout_done = true;
@@ -349,7 +349,8 @@ fn send(path: &Path, dst: &mut dyn Write) {
     t!(dst.write_all(&[0]));
     let mut file = t!(File::open(&path));
     let amt = t!(file.metadata()).len();
-    t!(dst.write_all(&[(amt >> 24) as u8, (amt >> 16) as u8, (amt >> 8) as u8, (amt >> 0) as u8,]));
+
+    t!(dst.write_all(&amt.to_be_bytes()));
     t!(io::copy(&mut file, dst));
 }
 
diff --git a/src/tools/remote-test-server/src/main.rs b/src/tools/remote-test-server/src/main.rs
index 3d61a0675590c..68d7aa56c438b 100644
--- a/src/tools/remote-test-server/src/main.rs
+++ b/src/tools/remote-test-server/src/main.rs
@@ -347,7 +347,7 @@ fn recv<B: BufRead>(dir: &Path, io: &mut B) -> PathBuf {
     // the filesystem limits.
     let len = cmp::min(filename.len() - 1, 50);
     let dst = dir.join(t!(str::from_utf8(&filename[..len])));
-    let amt = read_u32(io) as u64;
+    let amt = read_u64(io);
     t!(io::copy(&mut io.take(amt), &mut t!(File::create(&dst))));
     set_permissions(&dst);
     dst
@@ -365,7 +365,7 @@ fn my_copy(src: &mut dyn Read, which: u8, dst: &Mutex<dyn Write>) {
     loop {
         let n = t!(src.read(&mut b));
         let mut dst = dst.lock().unwrap();
-        t!(dst.write_all(&create_header(which, n as u32)));
+        t!(dst.write_all(&create_header(which, n as u64)));
         if n > 0 {
             t!(dst.write_all(&b[..n]));
         } else {
@@ -377,7 +377,7 @@ fn my_copy(src: &mut dyn Read, which: u8, dst: &Mutex<dyn Write>) {
 fn batch_copy(buf: &[u8], which: u8, dst: &Mutex<dyn Write>) {
     let n = buf.len();
     let mut dst = dst.lock().unwrap();
-    t!(dst.write_all(&create_header(which, n as u32)));
+    t!(dst.write_all(&create_header(which, n as u64)));
     if n > 0 {
         t!(dst.write_all(buf));
         // Marking buf finished
@@ -385,13 +385,13 @@ fn batch_copy(buf: &[u8], which: u8, dst: &Mutex<dyn Write>) {
     }
 }
 
-const fn create_header(which: u8, n: u32) -> [u8; 5] {
+const fn create_header(which: u8, n: u64) -> [u8; 9] {
     let bytes = n.to_be_bytes();
-    [which, bytes[0], bytes[1], bytes[2], bytes[3]]
+    [which, bytes[0], bytes[1], bytes[2], bytes[3], bytes[4], bytes[5], bytes[6], bytes[7]]
 }
 
-fn read_u32(r: &mut dyn Read) -> u32 {
-    let mut len = [0; 4];
+fn read_u64(r: &mut dyn Read) -> u64 {
+    let mut len = [0; 8];
     t!(r.read_exact(&mut len));
-    u32::from_be_bytes(len)
+    u64::from_be_bytes(len)
 }