1 files changed, 1 insertions, 1 deletions
diff --git a/juick-xmpp-ft/src/main/java/com/juick/components/XMPPFTServer.java b/juick-xmpp-ft/src/main/java/com/juick/components/XMPPFTServer.java
index e922e7fa..14d65de9 100644
--- a/juick-xmpp-ft/src/main/java/com/juick/components/XMPPFTServer.java
+++ b/juick-xmpp-ft/src/main/java/com/juick/components/XMPPFTServer.java
@@ -56,7 +56,7 @@ public class XMPPFTServer {
         fileTransferManager.addFileTransferOfferListener(e -> {
             try {
                 List<String> allowedTypes = new ArrayList<String>() {{ add("png"); add("jpg"); }};
-                String attachmentExtension = FilenameUtils.getExtension(e.getName());
+                String attachmentExtension = FilenameUtils.getExtension(e.getName()).toLowerCase();
                 String targetFilename = String.format("%s.%s",
                         DigestUtils.md5Hex(String.format("%s-%s",
                                 e.getInitiator().toString(), e.getSessionId()).getBytes()), attachmentExtension);