diff --git a/SabreTools.Helper/Tools/ArchiveTools.cs b/SabreTools.Helper/Tools/ArchiveTools.cs
index 94035808..b70b50cf 100644
--- a/SabreTools.Helper/Tools/ArchiveTools.cs
+++ b/SabreTools.Helper/Tools/ArchiveTools.cs
@@ -586,9 +586,9 @@ namespace SabreTools.Helper
 
 			// First line of defense is going to be the extension, for better or worse
 			string ext = Path.GetExtension(input).ToLowerInvariant();
-			if (ext != "7z" && ext != "gz" && ext != "lzma" && ext != "rar"
-				&& ext != "rev" && ext != "r00" && ext != "r01" && ext != "tar"
-				&& ext != "tgz" && ext != "tlz" && ext != "zip" && ext != "zipx")
+			if (ext != ".7z" && ext != ".gz" && ext != ".lzma" && ext != ".rar"
+				&& ext != ".rev" && ext != ".r00" && ext != ".r01" && ext != ".tar"
+				&& ext != ".tgz" && ext != ".tlz" && ext != ".zip" && ext != ".zipx")
 			{
 				return outtype;
 			}