diff --git a/src/swab.rs b/src/swab.rs
index 771d352..dd63587 100644
--- a/src/swab.rs
+++ b/src/swab.rs
@@ -75,20 +75,20 @@ fn main() -> ExitCode {
 				if let Err(e) = output.write(&right)
 						.and_then(|_| output.write(&left)) {
 					err(&argv[0], e);
-					break EX_IOERR // write error
+					break ExitCode::from(EX_IOERR as u8) // write error
 				}
 
 			},
 			Ok(v) => { // partial read; partially write
 				if let Err(e) = output.write(&buf[..v]) {
 					err(&argv[0], e);
-					break EX_IOERR // write error
+					break ExitCode::from(EX_IOERR as u8) // write error
 				}
 			},
 			Err(e) if e.kind() == ErrorKind::Interrupted && force => continue,
 			Err(e) => {
 				err(&argv[0], e);
-				break EX_IOERR // read error (or signal)
+				break ExitCode::from(EX_IOERR as u8) // read error (or signal)
 			}
 		}
 	}