diff --git a/src/main.rs b/src/main.rs
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,9 +2,15 @@ use regexp::Regexp;
 
 fn main() {
 	let tests = ["", "a", "ab", "aabb", "abab", "abcd", "abcbcdbcd"];
-	for pattern in ["a*b*", "a+b+", "(ab)*", "(ab)+", "a((bc)*d)*"] {
+	for pattern in ["*", "((a)", "a)", "+a"] {
 		println!("# {pattern}");
-		let r = Regexp::new(&pattern.to_string()).determinize();
+		let r = match Regexp::new(&pattern.to_string()) {
+			Ok(r1) => r1.determinize(),
+			Err(e) => {
+				println!("{e}");
+				continue;
+			}
+		};
 		for &t in tests.iter() {
 			println!("{t} {}", r.eval(t.to_string()));
 		}