diff --git a/tests/custom.rs b/tests/custom.rs
index 3904698..3b6f5c1 100644
--- a/tests/custom.rs
+++ b/tests/custom.rs
@@ -2,16 +2,16 @@ use romantic::Roman;
 
 use test_case::test_case;
 
-#[test_case(00, ""; "empty")]
-#[test_case(01, "A"; "one")]
-#[test_case(02, "AA"; "two")]
-#[test_case(03, "AAA"; "three")]
-#[test_case(04, "AB"; "four")]
-#[test_case(05, "B"; "five")]
-#[test_case(06, "BA"; "six")]
-#[test_case(07, "BAA"; "seven")]
-#[test_case(08, "BAAA"; "eight")]
-#[test_case(09, "AC"; "nine")]
+#[test_case(0, ""; "empty")]
+#[test_case(1, "A"; "one")]
+#[test_case(2, "AA"; "two")]
+#[test_case(3, "AAA"; "three")]
+#[test_case(4, "AB"; "four")]
+#[test_case(5, "B"; "five")]
+#[test_case(6, "BA"; "six")]
+#[test_case(7, "BAA"; "seven")]
+#[test_case(8, "BAAA"; "eight")]
+#[test_case(9, "AC"; "nine")]
 #[test_case(10, "C"; "ten")]
 fn test_to_string<T: num::PrimInt + num::Signed + ToString>(
   input: T,
@@ -21,16 +21,16 @@ fn test_to_string<T: num::PrimInt + num::Signed + ToString>(
   assert_eq!(custom.to_string(input).unwrap(), expected);
 }
 
-#[test_case("", 00; "empty")]
-#[test_case("A", 01; "one")]
-#[test_case("AA", 02; "two")]
-#[test_case("AAA", 03; "three")]
-#[test_case("AB", 04; "four")]
-#[test_case("B", 05; "five")]
-#[test_case("BA", 06; "six")]
-#[test_case("BAA", 07; "seven")]
-#[test_case("BAAA", 08; "eight")]
-#[test_case("AC", 09; "nine")]
+#[test_case("", 0; "empty")]
+#[test_case("A", 1; "one")]
+#[test_case("AA", 2; "two")]
+#[test_case("AAA", 3; "three")]
+#[test_case("AB", 4; "four")]
+#[test_case("B", 5; "five")]
+#[test_case("BA", 6; "six")]
+#[test_case("BAA", 7; "seven")]
+#[test_case("BAAA", 8; "eight")]
+#[test_case("AC", 9; "nine")]
 #[test_case("C", 10; "ten")]
 fn test_from_str(input: &str, expected: i32) {
   let custom = Roman::new(&['A', 'B', 'C', 'D']);
diff --git a/tests/default.rs b/tests/default.rs
index 0cd3ddb..c6ad61a 100644
--- a/tests/default.rs
+++ b/tests/default.rs
@@ -5,15 +5,15 @@ use test_case::test_case;
 #[test_case(0, ""; "empty")]
 #[test_case(3888, "MMMDCCCLXXXVIII"; "all characters")]
 #[test_case(3999, "MMMCMXCIX"; "maximum")]
-#[test_case(01, "I"; "one")]
-#[test_case(02, "II"; "two")]
-#[test_case(03, "III"; "three")]
-#[test_case(04, "IV"; "four")]
-#[test_case(05, "V"; "five")]
-#[test_case(06, "VI"; "six")]
-#[test_case(07, "VII"; "seven")]
-#[test_case(08, "VIII"; "eight")]
-#[test_case(09, "IX"; "nine")]
+#[test_case(1, "I"; "one")]
+#[test_case(2, "II"; "two")]
+#[test_case(3, "III"; "three")]
+#[test_case(4, "IV"; "four")]
+#[test_case(5, "V"; "five")]
+#[test_case(6, "VI"; "six")]
+#[test_case(7, "VII"; "seven")]
+#[test_case(8, "VIII"; "eight")]
+#[test_case(9, "IX"; "nine")]
 #[test_case(10, "X"; "ten")]
 fn test_to_string<T: num::PrimInt + num::Signed + ToString>(
   input: T,
@@ -25,15 +25,15 @@ fn test_to_string<T: num::PrimInt + num::Signed + ToString>(
 #[test_case("", 0; "empty")]
 #[test_case("MMMDCCCLXXXVIII", 3888; "complicated")]
 #[test_case("MMMCMXCIX", 3999; "maximum")]
-#[test_case("I", 01; "one")]
-#[test_case("II", 02; "two")]
-#[test_case("III", 03; "three")]
-#[test_case("IV", 04; "four")]
-#[test_case("V", 05; "five")]
-#[test_case("VI", 06; "six")]
-#[test_case("VII", 07; "seven")]
-#[test_case("VIII", 08; "eight")]
-#[test_case("IX", 09; "nine")]
+#[test_case("I", 1; "one")]
+#[test_case("II", 2; "two")]
+#[test_case("III", 3; "three")]
+#[test_case("IV", 4; "four")]
+#[test_case("V", 5; "five")]
+#[test_case("VI", 6; "six")]
+#[test_case("VII", 7; "seven")]
+#[test_case("VIII", 8; "eight")]
+#[test_case("IX", 9; "nine")]
 #[test_case("X", 10; "ten")]
 fn test_from_str(input: &str, expected: i32) {
   assert_eq!(Roman::default().from_str::<i32>(input).unwrap(), expected);