diff --git a/core/src/main/java/org/springframework/security/authentication/concurrent/ConcurrentSessionControllerImpl.java b/core/src/main/java/org/springframework/security/authentication/concurrent/ConcurrentSessionControllerImpl.java
index e4de3a14c5..106552b46a 100644
--- a/core/src/main/java/org/springframework/security/authentication/concurrent/ConcurrentSessionControllerImpl.java
+++ b/core/src/main/java/org/springframework/security/authentication/concurrent/ConcurrentSessionControllerImpl.java
@@ -88,10 +88,9 @@ public class ConcurrentSessionControllerImpl implements ConcurrentSessionControl
     public void checkAuthenticationAllowed(Authentication request) throws AuthenticationException {
         Assert.notNull(request, "Authentication request cannot be null (violation of interface contract)");
 
-        Object principal = SessionRegistryUtils.obtainPrincipalFromAuthentication(request);
-        String sessionId = SessionRegistryUtils.obtainSessionIdFromAuthentication(request);
+        String sessionId = obtainSessionId(request);
 
-        final List<SessionInformation> sessions = sessionRegistry.getAllSessions(principal, false);
+        final List<SessionInformation> sessions = sessionRegistry.getAllSessions(request.getPrincipal(), false);
 
         int sessionCount = sessions == null ? 0 : sessions.size();
 
@@ -137,10 +136,7 @@ public class ConcurrentSessionControllerImpl implements ConcurrentSessionControl
     public void registerSuccessfulAuthentication(Authentication authentication) {
         Assert.notNull(authentication, "Authentication cannot be null (violation of interface contract)");
 
-        Object principal = SessionRegistryUtils.obtainPrincipalFromAuthentication(authentication);
-        String sessionId = SessionRegistryUtils.obtainSessionIdFromAuthentication(authentication);
-
-        sessionRegistry.registerNewSession(sessionId, principal);
+        sessionRegistry.registerNewSession(obtainSessionId(authentication), authentication.getPrincipal());
     }
 
     public void setExceptionIfMaximumExceeded(boolean exceptionIfMaximumExceeded) {
@@ -162,4 +158,17 @@ public class ConcurrentSessionControllerImpl implements ConcurrentSessionControl
     public SessionRegistry getSessionRegistry() {
         return sessionRegistry;
     }
+
+    private String obtainSessionId(Authentication auth) {
+        if (auth.getDetails() == null || !(auth.getDetails() instanceof SessionIdentifierAware)) {
+            throw new IllegalArgumentException("The 'details' property of the supplied Authentication " +
+                    "object must be set and must implement 'SessionIdentifierAware', but Authentication.getDetails() " +
+                    "returned " + auth.getDetails());
+        }
+
+        String sessionId = ((SessionIdentifierAware) auth.getDetails()).getSessionId();
+        Assert.hasText(sessionId, "SessionIdentifierAware did not return a Session ID (" + auth.getDetails() + ")");
+
+        return sessionId;
+    }
 }
diff --git a/core/src/main/java/org/springframework/security/authentication/concurrent/SessionRegistryImpl.java b/core/src/main/java/org/springframework/security/authentication/concurrent/SessionRegistryImpl.java
index b6cc1df8c6..e988793c96 100644
--- a/core/src/main/java/org/springframework/security/authentication/concurrent/SessionRegistryImpl.java
+++ b/core/src/main/java/org/springframework/security/authentication/concurrent/SessionRegistryImpl.java
@@ -39,7 +39,6 @@ import org.springframework.util.Assert;
  * <p>
  * NB: It is important that you register the {@link org.springframework.security.web.session.HttpSessionEventPublisher} in
  * <code>web.xml</code> so that this class is notified of sessions that expire.
- * </p>
  *
  * @author Ben Alex
  * @version $Id$
diff --git a/core/src/main/java/org/springframework/security/authentication/concurrent/SessionRegistryUtils.java b/core/src/main/java/org/springframework/security/authentication/concurrent/SessionRegistryUtils.java
deleted file mode 100644
index 35147c2a80..0000000000
--- a/core/src/main/java/org/springframework/security/authentication/concurrent/SessionRegistryUtils.java
+++ /dev/null
@@ -1,60 +0,0 @@
-/* Copyright 2004, 2005, 2006 Acegi Technology Pty Limited
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.springframework.security.authentication.concurrent;
-
-
-import org.springframework.security.core.Authentication;
-import org.springframework.security.core.userdetails.UserDetails;
-
-import org.springframework.util.Assert;
-
-
-/**
- * Utility methods to assist with concurrent session management.
- *
- * @author Ben Alex
- * @version $Id$
- */
-public final class SessionRegistryUtils {
-    //~ Constructors ===================================================================================================
-
-    private SessionRegistryUtils() {
-    }
-
-    //~ Methods ========================================================================================================
-
-    public static Object obtainPrincipalFromAuthentication(Authentication auth) {
-        Assert.notNull(auth, "Authentication required");
-        Assert.notNull(auth.getPrincipal(), "Authentication.getPrincipal() required");
-
-        if (auth.getPrincipal() instanceof UserDetails) {
-            return ((UserDetails) auth.getPrincipal()).getUsername();
-        } else {
-            return auth.getPrincipal();
-        }
-    }
-
-    public static String obtainSessionIdFromAuthentication(Authentication auth) {
-        Assert.notNull(auth, "Authentication required");
-        Assert.notNull(auth.getDetails(), "Authentication.getDetails() required");
-        Assert.isInstanceOf(SessionIdentifierAware.class, auth.getDetails());
-
-        String sessionId = ((SessionIdentifierAware) auth.getDetails()).getSessionId();
-        Assert.hasText(sessionId, "SessionIdentifierAware did not return a Session ID (" + auth.getDetails() + ")");
-
-        return sessionId;
-    }
-}
diff --git a/web/src/main/java/org/springframework/security/web/util/SessionUtils.java b/web/src/main/java/org/springframework/security/web/util/SessionUtils.java
index 2b7afdb475..cf557c45b8 100644
--- a/web/src/main/java/org/springframework/security/web/util/SessionUtils.java
+++ b/web/src/main/java/org/springframework/security/web/util/SessionUtils.java
@@ -10,7 +10,6 @@ import javax.servlet.http.HttpSession;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.springframework.security.authentication.concurrent.SessionRegistry;
-import org.springframework.security.authentication.concurrent.SessionRegistryUtils;
 import org.springframework.security.core.context.SecurityContextHolder;
 
 /**
@@ -67,10 +66,8 @@ public final class SessionUtils {
 
         if (sessionRegistry != null) {
             sessionRegistry.removeSessionInformation(originalSessionId);
-            Object principal = SessionRegistryUtils.obtainPrincipalFromAuthentication(
-                    SecurityContextHolder.getContext().getAuthentication());
-
-            sessionRegistry.registerNewSession(session.getId(), principal);
+            sessionRegistry.registerNewSession(session.getId(),
+                    SecurityContextHolder.getContext().getAuthentication().getPrincipal());
         }
     }
 }