diff --git a/src/cli.rs b/src/cli.rs
index d161e11..b0f470e 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -4,7 +4,11 @@ use std::{
     time::Duration,
 };
 
-use clap::{Parser, builder::PossibleValuesParser};
+use clap::{
+    Parser,
+    builder::{PossibleValuesParser, TypedValueParser},
+    value_parser,
+};
 
 use super::{
     file::Checked,
@@ -43,7 +47,11 @@ pub struct Cli {
     max_views: u32,
 
     /// Chunk size for uploading, in MiB
-    #[arg(short, long, default_value_t = 10, value_name = "N")]
+    #[arg(
+        short, long,
+        default_value_t = 10, value_name = "M",
+        value_parser = value_parser!(u32).range(1..).map(|s| s as usize),
+    )]
     pub chunk_size: usize,
 
     /// Base URL for Sharry Instance