diff --git a/tools/knowledge.cs b/tools/knowledge.cs
index 0c605b7..406a264 100644
--- a/tools/knowledge.cs
+++ b/tools/knowledge.cs
@@ -59,7 +59,7 @@ using (var input = File.OpenRead(download))
 using (var file = File.Create(Path.Combine(output, "ip2asn.bin")))
   AsnTable.Write(file, sourceDate, Sources.IpToAsn(input));
 foreach (var stale in new[] { "networks.bin", "carriers.json", "registry.bin" }) File.Delete(Path.Combine(output, stale));
-string sha;
+var sha = default(string);
 using (var input = File.OpenRead(download)) sha = Convert.ToHexStringLower(SHA256.HashData(input));
 File.WriteAllText(Path.Combine(output, "SOURCE.txt"), $"iptoasn.com, Public Domain Dedication and License (PDDL) 1.0\n{Fallback}\nlast-modified {sourceDate:O}\nsha256 {sha}\n");
 Report();
diff --git a/tools/release.cs b/tools/release.cs
index 609d212..1d21940 100644
--- a/tools/release.cs
+++ b/tools/release.cs
@@ -365,7 +365,7 @@ string Reset(string folder)
   return folder;
 }
 
-string Size(string file) => $"{new FileInfo(file).Length / 1024.0 / 1024.0:0.0} MB";
+string Size(string file) => $"{new FileInfo(file).Length.ToMegabytes()} MB";
 
 string Option(string key)
 {
@@ -404,3 +404,8 @@ static string FindRoot()
   while (dir is not null && !File.Exists(Path.Combine(dir.FullName, "MeWeb.slnx"))) dir = dir.Parent;
   return dir?.FullName ?? throw new InvalidOperationException("run from inside the repository (MeWeb.slnx not found)");
 }
+
+static class NumbersExtensions
+{
+  public static string ToMegabytes(this long bytes) => (bytes / 1048576.0).ToString("0.0", System.Globalization.CultureInfo.InvariantCulture);
+}