diff --git a/core/src/main/java/com/muwire/core/Constants.java b/core/src/main/java/com/muwire/core/Constants.java
index 5e92f6ef..4c1ce2ad 100644
--- a/core/src/main/java/com/muwire/core/Constants.java
+++ b/core/src/main/java/com/muwire/core/Constants.java
@@ -4,6 +4,7 @@ import net.i2p.crypto.SigType;
 
 public class Constants {
     public static final byte PERSONA_VERSION = (byte)1;
+    public static final String INVALID_NICKNAME_CHARS = "'\"();<>=@$%";
     public static final byte FILE_CERT_VERSION = (byte)2;
     public static final int CHAT_VERSION = 1;
     
diff --git a/core/src/main/java/com/muwire/core/InvalidNicknameException.java b/core/src/main/java/com/muwire/core/InvalidNicknameException.java
new file mode 100644
index 00000000..d1c275fc
--- /dev/null
+++ b/core/src/main/java/com/muwire/core/InvalidNicknameException.java
@@ -0,0 +1,25 @@
+package com.muwire.core;
+
+public class InvalidNicknameException extends Exception {
+
+    public InvalidNicknameException() {
+    }
+
+    public InvalidNicknameException(String message) {
+        super(message);
+    }
+
+    public InvalidNicknameException(Throwable cause) {
+        super(cause);
+    }
+
+    public InvalidNicknameException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public InvalidNicknameException(String message, Throwable cause, boolean enableSuppression,
+            boolean writableStackTrace) {
+        super(message, cause, enableSuppression, writableStackTrace);
+    }
+
+}
diff --git a/core/src/main/java/com/muwire/core/Persona.java b/core/src/main/java/com/muwire/core/Persona.java
index 54d9bdb2..03a5f5a9 100644
--- a/core/src/main/java/com/muwire/core/Persona.java
+++ b/core/src/main/java/com/muwire/core/Persona.java
@@ -7,6 +7,8 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 
+import com.muwire.core.util.DataUtil;
+
 import net.i2p.crypto.DSAEngine;
 import net.i2p.data.Base64;
 import net.i2p.data.DataFormatException;
@@ -25,12 +27,15 @@ public class Persona {
     private volatile String base64;
     private volatile byte[] payload;
 
-    public Persona(InputStream personaStream) throws IOException, DataFormatException, InvalidSignatureException {
+    public Persona(InputStream personaStream) throws IOException, DataFormatException, InvalidSignatureException, InvalidNicknameException {
         version = (byte) (personaStream.read() & 0xFF);
         if (version != Constants.PERSONA_VERSION)
             throw new IOException("Unknown version "+version);
 
         name = new Name(personaStream);
+        if (!DataUtil.isValidName(name.name))
+            throw new InvalidNicknameException(name.name + " is not a valid nickname");
+        
         destination = Destination.create(personaStream);
         sig = new byte[SIG_LEN];
         DataInputStream dis = new DataInputStream(personaStream);
@@ -38,7 +43,7 @@ public class Persona {
         if (!verify(version, name, destination, sig))
             throw new InvalidSignatureException(getHumanReadableName() + " didn't verify");
     }
-
+    
     private static boolean verify(byte version, Name name, Destination destination, byte [] sig) 
     throws IOException, DataFormatException {
         ByteArrayOutputStream baos = new ByteArrayOutputStream();
diff --git a/core/src/main/java/com/muwire/core/util/DataUtil.java b/core/src/main/java/com/muwire/core/util/DataUtil.java
index 9371d697..bdd2a77b 100644
--- a/core/src/main/java/com/muwire/core/util/DataUtil.java
+++ b/core/src/main/java/com/muwire/core/util/DataUtil.java
@@ -216,4 +216,11 @@ public class DataUtil {
         Signature sig = DSAEngine.getInstance().sign(payload, spk);
         return sig.getData();
     }
+    
+    public static boolean isValidName(String name) {
+        for (int i = 0; i < Constants.INVALID_NICKNAME_CHARS.length(); i++)
+            if (name.indexOf(Constants.INVALID_NICKNAME_CHARS.charAt(i)) >= 0)
+                return false;
+        return true;
+    }
 }
diff --git a/gui/griffon-app/lifecycle/Ready.groovy b/gui/griffon-app/lifecycle/Ready.groovy
index 311cdbfb..90130fa8 100644
--- a/gui/griffon-app/lifecycle/Ready.groovy
+++ b/gui/griffon-app/lifecycle/Ready.groovy
@@ -6,10 +6,12 @@ import net.i2p.util.SystemVersion
 
 import org.codehaus.griffon.runtime.core.AbstractLifecycleHandler
 
+import com.muwire.core.Constants
 import com.muwire.core.Core
 import com.muwire.core.MuWireSettings
 import com.muwire.core.UILoadedEvent
 import com.muwire.core.files.FileSharedEvent
+import com.muwire.core.util.DataUtil
 
 import javax.annotation.Nonnull
 import javax.inject.Inject
@@ -116,8 +118,8 @@ class Ready extends AbstractLifecycleHandler {
                         JOptionPane.WARNING_MESSAGE)
                 continue
             }
-            if (nickname.contains("@")) {
-                JOptionPane.showMessageDialog(null, "Nickname cannot contain @, choose another",
+            if (!DataUtil.isValidName(nickname)) {
+                JOptionPane.showMessageDialog(null, "Nickname cannot contain any of ${Constants.INVALID_NICKNAME_CHARS} choose another",
                         "Select another nickname", JOptionPane.WARNING_MESSAGE)
                 continue
             }