diff --git a/lib/system-performance.ts b/lib/system-performance.ts
index ad63413..f285206 100644
--- a/lib/system-performance.ts
+++ b/lib/system-performance.ts
@@ -17,7 +17,7 @@ const CGROUP_V2_CURRENT = '/sys/fs/cgroup/memory.current'
 const CGROUP_V2_MAX = '/sys/fs/cgroup/memory.max'
 const CGROUP_V1_USAGE = '/sys/fs/cgroup/memory/memory.usage_in_bytes'
 const CGROUP_V1_LIMIT = '/sys/fs/cgroup/memory/memory.limit_in_bytes'
-const CGROUP_UNLIMITED = 1n << 60n
+const CGROUP_UNLIMITED = BigInt(1) << BigInt(60)
 
 type FileReader = (path: string) => Promise<string>
 
@@ -26,7 +26,7 @@ async function readNumericFile(read: FileReader, path: string): Promise<bigint |
     const raw = (await read(path)).trim()
     if (!raw || raw === 'max') return null
     const value = BigInt(raw)
-    return value >= 0n ? value : null
+    return value >= BigInt(0) ? value : null
   } catch {
     return null
   }