diff --git a/.changeset/green-snakes-try.md b/.changeset/green-snakes-try.md
new file mode 100644
index 0000000..083afa8
--- /dev/null
+++ b/.changeset/green-snakes-try.md
@@ -0,0 +1,5 @@
+---
+'multitars': patch
+---
+
+Replace `parseInt(val, 8)` for octal parsing with manual parsing (hotpath)
diff --git a/src/tarInput.ts b/src/tarInput.ts
index ffd5a56..b878e3d 100644
--- a/src/tarInput.ts
+++ b/src/tarInput.ts
@@ -146,8 +146,9 @@ function decodeOctal(bytes: Uint8Array, from: number, to: number): number {
   } else {
     idx = from;
     while (idx < to && (bytes[idx] === 32 || bytes[idx] === 0)) idx++;
-    if (end !== idx) val = parseInt(decodeString(bytes, idx, to), 8);
-    return val == val ? val || 0 : 0;
+    while (idx < to && bytes[idx] >= 48 && bytes[idx] <= 55)
+      val = val * 8 + (bytes[idx++] - 48);
+    return val;
   }
 }