diff --git a/src/keepass2android/EntryActivity.cs b/src/keepass2android/EntryActivity.cs
index 5576a795..52c5441b 100644
--- a/src/keepass2android/EntryActivity.cs
+++ b/src/keepass2android/EntryActivity.cs
@@ -657,7 +657,7 @@ namespace keepass2android
 			if (extension != null)
 			{
 				MimeTypeMap mime = MimeTypeMap.Singleton;
-				type = mime.GetMimeTypeFromExtension(extension);
+				type = mime.GetMimeTypeFromExtension(extension.ToLowerInvariant());
 			}
 			return type;
 		}