diff --git a/buildSrc/build.gradle b/buildSrc/build.gradle
index ac78628d27..af9cd4b2b4 100644
--- a/buildSrc/build.gradle
+++ b/buildSrc/build.gradle
@@ -30,7 +30,7 @@ dependencies {
 
 // GAE
 dependencies {
-    compile 'com.google.appengine:appengine-tools-api:1.3.5'
+    compile 'com.google.appengine:appengine-tools-api:1.3.7'
 }
 
 task ide(type: Copy)  {
diff --git a/buildSrc/src/main/groovy/gae/GaePlugin.groovy b/buildSrc/src/main/groovy/gae/GaePlugin.groovy
index e028d01b03..b131c8c316 100644
--- a/buildSrc/src/main/groovy/gae/GaePlugin.groovy
+++ b/buildSrc/src/main/groovy/gae/GaePlugin.groovy
@@ -20,7 +20,7 @@ class GaePlugin implements Plugin<Project> {
         project.gaeDeploy.dependsOn project.war
 
         project.war.doLast {
-          ant.unzip(src: project.war.archivePath, dest: explodedWar)
+            ant.unzip(src: project.war.archivePath, dest: explodedWar)
         }
     }
 }
diff --git a/samples/gae/gae.gradle b/samples/gae/gae.gradle
index 6c5bf73a48..06eee6e93d 100644
--- a/samples/gae/gae.gradle
+++ b/samples/gae/gae.gradle
@@ -2,7 +2,7 @@ apply plugin: 'war'
 apply plugin: 'jetty'
 apply plugin: 'gae'
 
-gaeVersion="1.3.5"
+gaeVersion="1.3.7"
 
 repositories {
     // Hibernate Validator
@@ -15,8 +15,7 @@ repositories {
 configurations.runtime.exclude(group: 'ch.qos.logback')
 
 dependencies {
-    providedCompile 'javax.servlet:servlet-api:2.5@jar',
-                    "com.google.appengine:appengine-api-1.0-sdk:$gaeVersion"
+    providedCompile 'javax.servlet:servlet-api:2.5@jar'
 
     compile project(':spring-security-core'),
             project(':spring-security-web'),
@@ -25,11 +24,13 @@ dependencies {
             "org.springframework:spring-webmvc:$springVersion",
             "org.springframework:spring-context:$springVersion",
             "org.springframework:spring-context-support:$springVersion",
+            "com.google.appengine:appengine-api-1.0-sdk:$gaeVersion",
             'javax.validation:validation-api:1.0.0.GA',
             'org.hibernate:hibernate-validator:4.1.0.Final',
             "org.slf4j:slf4j-api:$slf4jVersion"
 
     runtime project(':spring-security-config'),
+            project(':spring-security-taglibs'),
             "org.slf4j:jcl-over-slf4j:$slf4jVersion",
             "org.slf4j:slf4j-jdk14:$slf4jVersion"
     testCompile "com.google.appengine:appengine-testing:$gaeVersion"
diff --git a/samples/gae/src/main/java/samples/gae/security/GaeAuthenticationFilter.java b/samples/gae/src/main/java/samples/gae/security/GaeAuthenticationFilter.java
index f8edd5e009..48d35fa3b4 100644
--- a/samples/gae/src/main/java/samples/gae/security/GaeAuthenticationFilter.java
+++ b/samples/gae/src/main/java/samples/gae/security/GaeAuthenticationFilter.java
@@ -24,6 +24,7 @@ import org.springframework.security.web.authentication.WebAuthenticationDetailsS
 import org.springframework.security.web.authentication.preauth.PreAuthenticatedAuthenticationToken;
 import org.springframework.util.Assert;
 import org.springframework.web.filter.GenericFilterBean;
+import samples.gae.users.GaeUser;
 
 /**
  * @author Luke Taylor
@@ -39,10 +40,15 @@ public class GaeAuthenticationFilter extends GenericFilterBean {
 
     public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
         Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+        User googleUser = UserServiceFactory.getUserService().getCurrentUser();
 
-        if (authentication == null) {
-            User googleUser = UserServiceFactory.getUserService().getCurrentUser();
+        if (authentication != null && !loggedInUserMatchesGaeUser(authentication, googleUser)) {
+            SecurityContextHolder.clearContext();
+            authentication = null;
+            ((HttpServletRequest)request).getSession().invalidate();
+        }
 
+        if (authentication == null) {
             if (googleUser != null) {
                 logger.debug("Currently logged on to GAE as user " + googleUser);
                 logger.debug("Authenticating to Spring Security");
@@ -72,6 +78,24 @@ public class GaeAuthenticationFilter extends GenericFilterBean {
         chain.doFilter(request, response);
     }
 
+    private boolean loggedInUserMatchesGaeUser(Authentication authentication, User googleUser) {
+        assert authentication != null;
+
+        if (googleUser == null) {
+            // User has logged out of GAE but is still logged into application
+            return false;
+        }
+
+        GaeUser gaeUser = (GaeUser)authentication.getPrincipal();
+
+        if (!gaeUser.getEmail().equals(googleUser.getEmail())) {
+            return false;
+        }
+
+        return true;
+
+    }
+
     @Override
     public void afterPropertiesSet() throws ServletException {
         Assert.notNull(authenticationManager, "AuthenticationManager must be set");