diff --git a/kclvm/lexer/src/number.rs b/kclvm/lexer/src/number.rs
index f9f7d9ab2..0458b1fd1 100644
--- a/kclvm/lexer/src/number.rs
+++ b/kclvm/lexer/src/number.rs
@@ -66,7 +66,7 @@ impl<'a> Cursor<'a> {
                 // with a number
                 self.bump();
                 let mut empty_exponent = false;
-                if self.peek().is_digit(10) {
+                if self.peek().is_ascii_digit() {
                     self.eat_decimal_digits();
                     match self.peek() {
                         'e' | 'E' => {
diff --git a/kclvm/lexer/src/tests.rs b/kclvm/lexer/src/tests.rs
index 2bd614658..6b430f45e 100644
--- a/kclvm/lexer/src/tests.rs
+++ b/kclvm/lexer/src/tests.rs
@@ -1,10 +1,12 @@
 use super::*;
 use expect_test::{expect, Expect};
+use std::fmt::Write;
 
 fn check_lexing(src: &str, expect: Expect) {
-    let actual: String = tokenize(src)
-        .map(|token| format!("{:?}\n", token))
-        .collect();
+    let actual: String = tokenize(src).fold(String::new(), |mut acc, token| {
+        writeln!(acc, "{:?}", token).expect("Failed to write to string");
+        acc
+    });
     expect.assert_eq(&actual)
 }