diff --git a/Source/Generator.Rewrite/Program.cs b/Source/Generator.Rewrite/Program.cs
index 873d6e45..a204eab3 100644
--- a/Source/Generator.Rewrite/Program.cs
+++ b/Source/Generator.Rewrite/Program.cs
@@ -82,7 +82,7 @@ namespace OpenTK.Rewrite
             if (!String.IsNullOrEmpty(keyfile) && File.Exists(keyfile))
             {
                 keyfile = Path.GetFullPath(keyfile);
-                var fs = new FileStream(keyfile, FileMode.Open);
+                var fs = new FileStream(keyfile, FileMode.Open, FileAccess.Read);
                 var keypair = new System.Reflection.StrongNameKeyPair(fs);
                 fs.Close();
                 write_params.StrongNameKeyPair = keypair;