diff --git a/src/cli/args.zig b/src/cli/args.zig
index ea0549da0..be71b9096 100644
--- a/src/cli/args.zig
+++ b/src/cli/args.zig
@@ -319,6 +319,7 @@ pub fn parseIntoField(
 
                 inline u8,
                 u16,
+                u21,
                 u32,
                 u64,
                 usize,