diff --git a/src/main/java/eu/siacs/conversations/generator/IqGenerator.java b/src/main/java/eu/siacs/conversations/generator/IqGenerator.java
index cb9ffd96..8393a011 100644
--- a/src/main/java/eu/siacs/conversations/generator/IqGenerator.java
+++ b/src/main/java/eu/siacs/conversations/generator/IqGenerator.java
@@ -10,12 +10,15 @@ import org.whispersystems.libaxolotl.ecc.ECPublicKey;
 import org.whispersystems.libaxolotl.state.PreKeyRecord;
 import org.whispersystems.libaxolotl.state.SignedPreKeyRecord;
 
+import java.math.BigInteger;
+import java.nio.ByteBuffer;
 import java.security.cert.CertificateEncodingException;
 import java.security.cert.X509Certificate;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Set;
 import java.util.TimeZone;
+import java.util.UUID;
 
 import eu.siacs.conversations.Config;
 import eu.siacs.conversations.R;
@@ -315,7 +318,7 @@ public class IqGenerator extends AbstractGenerator {
 		IqPacket packet = new IqPacket(IqPacket.TYPE.GET);
 		packet.setTo(host);
 		Element request = packet.addChild("request", Xmlns.HTTP_UPLOAD);
-		request.addChild("filename").setContent(file.getName());
+		request.addChild("filename").setContent(convertFilename(file.getName()));
 		request.addChild("size").setContent(String.valueOf(file.getExpectedSize()));
 		if (mime != null) {
 			request.addChild("content-type").setContent(mime);
@@ -323,6 +326,23 @@ public class IqGenerator extends AbstractGenerator {
 		return packet;
 	}
 
+	private static String convertFilename(String name) {
+		int pos = name.indexOf('.');
+		if (pos != -1) {
+			try {
+				UUID uuid = UUID.fromString(name.substring(0, pos));
+				ByteBuffer bb = ByteBuffer.wrap(new byte[16]);
+				bb.putLong(uuid.getMostSignificantBits());
+				bb.putLong(uuid.getLeastSignificantBits());
+				return Base64.encodeToString(bb.array(), Base64.URL_SAFE) + name.substring(pos, name.length());
+			} catch (Exception e) {
+				return name;
+			}
+		} else {
+			return name;
+		}
+	}
+
 	public IqPacket generateCreateAccountWithCaptcha(Account account, String id, Data data) {
 		final IqPacket register = new IqPacket(IqPacket.TYPE.SET);
 		register.setFrom(account.getJid().toBareJid());
diff --git a/src/main/java/eu/siacs/conversations/xmpp/XmppConnection.java b/src/main/java/eu/siacs/conversations/xmpp/XmppConnection.java
index ef5ff854..d80f44f4 100644
--- a/src/main/java/eu/siacs/conversations/xmpp/XmppConnection.java
+++ b/src/main/java/eu/siacs/conversations/xmpp/XmppConnection.java
@@ -1255,7 +1255,7 @@ public class XmppConnection implements Runnable {
 	}
 
 	private String nextRandomId() {
-		return new BigInteger(50, mXmppConnectionService.getRNG()).toString(32);
+		return new BigInteger(50, mXmppConnectionService.getRNG()).toString(36);
 	}
 
 	public String sendIqPacket(final IqPacket packet, final OnIqPacketReceived callback) {