diff --git a/crates/oxc_mangler/Cargo.toml b/crates/oxc_mangler/Cargo.toml
index 07df3485301ae..0d3d675cd6fb5 100644
--- a/crates/oxc_mangler/Cargo.toml
+++ b/crates/oxc_mangler/Cargo.toml
@@ -17,7 +17,7 @@ description.workspace = true
 workspace = true
 
 [lib]
-test = false
+test = true
 doctest = false
 
 [dependencies]
diff --git a/crates/oxc_mangler/src/base54.rs b/crates/oxc_mangler/src/base54.rs
index 9b4ecfe4741dd..fe5d52adc3fdc 100644
--- a/crates/oxc_mangler/src/base54.rs
+++ b/crates/oxc_mangler/src/base54.rs
@@ -33,15 +33,15 @@ const BASE54_CHARS: Aligned64 =
 /// Get the shortest mangled name for a given n.
 /// Code adapted from [terser](https://github.com/terser/terser/blob/8b966d687395ab493d2c6286cc9dd38650324c11/lib/scope.js#L1041-L1051)
 //
-// Maximum length of string is 11 (`ZrN6rN6rN6r` for `u64::MAX`), but set `CAPACITY` as 12,
-// so the total size of `InlineString` is 16, including the `len` field.
-// Then initializing the `InlineString` is a single `xmm` set, and with luck it'll sit in a register
+// Maximum length of string is 6 (`xKrTKr` for `u32::MAX`), but set `CAPACITY` as 7,
+// so the total size of `InlineString` is 8, including the `u8` length field.
+// Then initializing the `InlineString` is a single instruction, and with luck it'll sit in a register
 // throughout this function.
 #[expect(clippy::items_after_statements)]
-pub fn base54(n: usize) -> InlineString<12, u32> {
+pub fn base54(n: u32) -> InlineString<7, u8> {
     let mut str = InlineString::new();
 
-    let mut num = n;
+    let mut num = n as usize;
 
     // Base 54 at first because these are the usable first characters in JavaScript identifiers
     // <https://tc39.es/ecma262/#prod-IdentifierStart>
@@ -72,21 +72,11 @@ mod test {
 
     #[test]
     fn test_base54() {
-        assert_eq!(&*base54(0), "a");
-        assert_eq!(&*base54(25), "z");
-        assert_eq!(&*base54(26), "A");
-        assert_eq!(&*base54(51), "Z");
-        assert_eq!(&*base54(52), "$");
-        assert_eq!(&*base54(53), "_");
-        assert_eq!(&*base54(54), "aa");
-        assert_eq!(&*base54(55), "ab");
-
-        if cfg!(target_pointer_width = "64") {
-            assert_eq!(&*base54(usize::MAX), "ZrN6rN6rN6r");
-        }
-
-        if cfg!(target_pointer_width = "32") {
-            assert_eq!(&*base54(usize::MAX), "vUdzUd");
-        }
+        assert_eq!(&*base54(0), "e");
+        assert_eq!(&*base54(52), "Q");
+        assert_eq!(&*base54(53), "$");
+        assert_eq!(&*base54(54), "ee");
+        assert_eq!(&*base54(55), "te");
+        assert_eq!(&*base54(u32::MAX), "xKrTKr");
     }
 }
diff --git a/crates/oxc_mangler/src/lib.rs b/crates/oxc_mangler/src/lib.rs
index cfadc6ca077f2..f675d001a2ed4 100644
--- a/crates/oxc_mangler/src/lib.rs
+++ b/crates/oxc_mangler/src/lib.rs
@@ -185,7 +185,7 @@ impl Mangler {
 
     fn build_with_symbols_and_scopes_impl<
         const CAPACITY: usize,
-        G: Fn(usize) -> InlineString<CAPACITY, u32>,
+        G: Fn(u32) -> InlineString<CAPACITY, u8>,
     >(
         self,
         semantic: Semantic<'_>,
@@ -450,9 +450,8 @@ fn is_keyword(s: &str) -> bool {
             | "void" | "with")
 }
 
-// Maximum length of string is 25 (`slot_18446744073709551615` for `u64::MAX`)
-// but set `CAPACITY` as 28 so the total size of `InlineString` is 32, including the `u32` length.
-fn debug_name(n: usize) -> InlineString<28, u32> {
+// Maximum length of string is 15 (`slot_4294967295` for `u32::MAX`).
+fn debug_name(n: u32) -> InlineString<15, u8> {
     // Using `format!` here allocates a string unnecessarily.
     // But this function is not for use in production, so let's not worry about it.
     // We shouldn't resort to unsafe code, when it's not critical for performance.