diff --git a/src/main/scala/app/ControllerBase.scala b/src/main/scala/app/ControllerBase.scala
index 31eac0e..a8226c6 100644
--- a/src/main/scala/app/ControllerBase.scala
+++ b/src/main/scala/app/ControllerBase.scala
@@ -63,11 +63,7 @@
     request.getRequestURI + (if(queryString != null) "?" + queryString else "")
   }
 
-  private def LoginAccount: Option[Account] =
-    session.get("LOGIN_ACCOUNT") match {
-      case Some(x: Account) => Some(x)
-      case _ => None
-    }
+  private def LoginAccount: Option[Account] = session.getAs[Account]("LOGIN_ACCOUNT")
 
   def ajaxGet(path : String)(action : => Any) : Route =
     super.get(path){
diff --git a/src/main/scala/app/DashboardController.scala b/src/main/scala/app/DashboardController.scala
index b0509dd..16fa0cb 100644
--- a/src/main/scala/app/DashboardController.scala
+++ b/src/main/scala/app/DashboardController.scala
@@ -78,7 +78,7 @@
     val sessionKey = "dashboard/pulls"
     val condition = session.putAndGet(sessionKey, {
       if(request.hasQueryString) IssueSearchCondition(request)
-      else session.get(sessionKey).getOrElse(IssueSearchCondition()).asInstanceOf[IssueSearchCondition]
+      else session.getAs[IssueSearchCondition](sessionKey).getOrElse(IssueSearchCondition())
     }.copy(repo = repository))
 
     val userName = context.loginAccount.get.userName
diff --git a/src/main/scala/app/IssuesController.scala b/src/main/scala/app/IssuesController.scala
index b4f5376..9adab7c 100644
--- a/src/main/scala/app/IssuesController.scala
+++ b/src/main/scala/app/IssuesController.scala
@@ -333,7 +333,7 @@
       // retrieve search condition
       val condition = session.putAndGet(sessionKey,
         if(request.hasQueryString) IssueSearchCondition(request)
-        else session.get(sessionKey).getOrElse(IssueSearchCondition()).asInstanceOf[IssueSearchCondition]
+        else session.getAs[IssueSearchCondition](sessionKey).getOrElse(IssueSearchCondition())
       )
 
       issues.html.list(
diff --git a/src/main/scala/app/PullRequestsController.scala b/src/main/scala/app/PullRequestsController.scala
index 5d4ec90..6ee5c34 100644
--- a/src/main/scala/app/PullRequestsController.scala
+++ b/src/main/scala/app/PullRequestsController.scala
@@ -374,7 +374,7 @@
       // retrieve search condition
       val condition = session.putAndGet(sessionKey,
         if(request.hasQueryString) IssueSearchCondition(request)
-        else session.get(sessionKey).getOrElse(IssueSearchCondition()).asInstanceOf[IssueSearchCondition]
+        else session.getAs[IssueSearchCondition](sessionKey).getOrElse(IssueSearchCondition())
       )
 
       pulls.html.list(
diff --git a/src/main/scala/app/SignInController.scala b/src/main/scala/app/SignInController.scala
index 3b56301..79d946e 100644
--- a/src/main/scala/app/SignInController.scala
+++ b/src/main/scala/app/SignInController.scala
@@ -2,6 +2,7 @@
 
 import service._
 import jp.sf.amateras.scalatra.forms._
+import util.Implicits._
 
 class SignInController extends SignInControllerBase with SystemSettingsService with AccountService
 
@@ -25,7 +26,7 @@
   post("/signin", form){ form =>
     authenticate(loadSystemSettings(), form.userName, form.password) match {
       case Some(account) => signin(account)
-      case None => redirect("/signin")
+      case None          => redirect("/signin")
     }
   }
 
@@ -41,8 +42,7 @@
     session.setAttribute("LOGIN_ACCOUNT", account)
     updateLastLoginDate(account.userName)
 
-    session.get("REDIRECT").map { case redirectUrl: String =>
-      session.removeAttribute("REDIRECT")
+    session.getAndRemove[String]("REDIRECT").map { redirectUrl =>
       if(redirectUrl.replaceFirst("/$", "") == request.getContextPath){
         redirect("/")
       } else {
diff --git a/src/main/scala/util/Implicits.scala b/src/main/scala/util/Implicits.scala
index 75d34b3..957a030 100644
--- a/src/main/scala/util/Implicits.scala
+++ b/src/main/scala/util/Implicits.scala
@@ -54,10 +54,19 @@
   }
 
   implicit class RichSession(session: HttpSession){
+
     def putAndGet[T](key: String, value: T): T = {
       session.setAttribute(key, value)
       value
     }
+
+    def getAndRemove[T](key: String): Option[T] = {
+      val value = session.getAttribute(key).asInstanceOf[T]
+      if(value == null){
+        session.removeAttribute(key)
+      }
+      Option(value)
+    }
   }
 
 }
\ No newline at end of file