diff --git a/src/fop.rs b/src/fop.rs
index 6bb778c..a58f759 100644
--- a/src/fop.rs
+++ b/src/fop.rs
@@ -72,7 +72,7 @@ fn main() -> ExitCode {
 	/* parse the specified index as a number we can use */
 	let index = argv[optind].parse::<usize>().unwrap_or_else(|e| {
 		eprintln!("{}: {}: {}", argv[0], argv[1], e);
-		exit(EX_DATAERR as i32);
+		exit(EX_DATAERR.into());
 	});
 
 	/* index of the argv[0] for the operator command */
@@ -80,14 +80,14 @@ fn main() -> ExitCode {
 
 	/* argv[0] of the operator command */
 	let operator = argv.get(command_arg).unwrap_or_else(|| {
-		exit(usage(&argv[0]) as i32);
+		exit(usage(&argv[0]).into());
 	});
 
 	/* read entire standard input into memory */
 	let mut buf = String::new();
 	if let Err(e) = stdin().read_to_string(&mut buf) {
 		err(&argv[0], e);
-		exit(EX_IOERR as i32);
+		exit(EX_IOERR.into());
 	};
 
 	/* split the buffer by the delimiter (by default, '\u{1E}') */
@@ -108,13 +108,13 @@ fn main() -> ExitCode {
 		.spawn()
 		.unwrap_or_else( |e| {
 			err(&argv[0], e);
-			exit(EX_UNAVAILABLE as i32);
+			exit(EX_UNAVAILABLE.into());
 		});
 
 	/* get field we want to pipe into spawned program */
 	let field = fields.get(index).unwrap_or_else(|| {
 		eprintln!("{}: {}: no such index in input", argv[0], index);
-		exit(EX_DATAERR as i32);
+		exit(EX_DATAERR.into());
 	});
 
 	/* get the stdin of the newly spawned program and feed it the field val */
@@ -125,7 +125,7 @@ fn main() -> ExitCode {
 
 	let output = spawned.wait_with_output().unwrap_or_else(|e| {
 		err(&argv[0], e);
-		exit(EX_IOERR as i32);
+		exit(EX_IOERR.into());
 	});
 
 	/* get the output with which the original field will be replaced */
@@ -142,7 +142,7 @@ fn main() -> ExitCode {
 	/* convert the output of the program to UTF-8 */
 	let new_field = String::from_utf8(replace).unwrap_or_else(|e| {
 		eprintln!("{}: {}", argv[0], e);
-		exit(EX_IOERR as i32);
+		exit(EX_IOERR.into());
 	});
 
 	/* store the new field in the old fields vector */
@@ -153,7 +153,7 @@ fn main() -> ExitCode {
 		fields.join(&d.to_string()).as_bytes()
 	).unwrap_or_else(|e| {
 		err(&argv[0], e);
-		exit(EX_IOERR as i32);
+		exit(EX_IOERR.into());
 	});
 
 	ExitCode::SUCCESS