diff --git a/repos/os/include/vfs/types.h b/repos/os/include/vfs/types.h
index 917f795cb..a004162ed 100644
--- a/repos/os/include/vfs/types.h
+++ b/repos/os/include/vfs/types.h
@@ -51,8 +51,8 @@ namespace Vfs {
 
 	struct Timestamp
 	{
-		static constexpr long long INVALID = (1LL << 63) + 1;
-		long long value;
+		static constexpr Genode::int64_t INVALID = 0x7fffffffffffffffLL;
+		Genode::int64_t value;
 	};
 
 	enum class Node_type {
diff --git a/repos/ports/src/lib/libc_noux/plugin.cc b/repos/ports/src/lib/libc_noux/plugin.cc
index 0a9cb6fa0..a2d6b7b60 100644
--- a/repos/ports/src/lib/libc_noux/plugin.cc
+++ b/repos/ports/src/lib/libc_noux/plugin.cc
@@ -419,7 +419,7 @@ static void _sysio_to_stat_struct(Noux::Sysio const *sysio, struct stat *buf)
 	buf->st_ino     = src.inode;
 	buf->st_dev     = src.device;
 
-	if (src.modification_time.value >= 0)
+	if (src.modification_time.value != Vfs::Timestamp::INVALID)
 		buf->st_mtime = src.modification_time.value;
 }