diff --git a/src/main/scala/gitbucket/core/controller/PrioritiesController.scala b/src/main/scala/gitbucket/core/controller/PrioritiesController.scala
index 3adae1a..ab24b59 100644
--- a/src/main/scala/gitbucket/core/controller/PrioritiesController.scala
+++ b/src/main/scala/gitbucket/core/controller/PrioritiesController.scala
@@ -72,7 +72,7 @@
   })
 
   ajaxPost("/:owner/:repository/issues/priorities/default")(writableUsersOnly { (repository) =>
-    setDefaultPriority(repository.owner, repository.name, params("priorityId").toInt)
+    setDefaultPriority(repository.owner, repository.name, priorityId("priorityId"))
     Ok()
   })
 
@@ -81,6 +81,8 @@
     Ok()
   })
 
+  val priorityId: String => Option[Int] = (key: String) => params.get(key).flatMap(_.toIntOpt)
+
   /**
    * Constraint for the identifier such as user name, repository name or page name.
    */
diff --git a/src/main/scala/gitbucket/core/service/PrioritiesService.scala b/src/main/scala/gitbucket/core/service/PrioritiesService.scala
index f5a867d..fa4e405 100644
--- a/src/main/scala/gitbucket/core/service/PrioritiesService.scala
+++ b/src/main/scala/gitbucket/core/service/PrioritiesService.scala
@@ -24,14 +24,12 @@
       .map(m => m + 1)
       .getOrElse(0)
 
-    val isDefault = getDefaultPriority(owner, repository).isEmpty
-
     Priorities returning Priorities.map(_.priorityId) insert Priority(
       userName       = owner,
       repositoryName = repository,
       priorityName   = priorityName,
       description    = StringUtil.emptyToNone(description),
-      isDefault      = isDefault,
+      isDefault      = false,
       ordering       = ordering,
       color          = color
     )
@@ -71,16 +69,16 @@
       .headOption
   }
 
-  def setDefaultPriority(owner: String, repository: String, priorityId: Int)(implicit s: Session): Unit = {
+  def setDefaultPriority(owner: String, repository: String, priorityId: Option[Int])(implicit s: Session): Unit = {
     Priorities
       .filter(_.byRepository(owner, repository))
       .filter(_.isDefault)
       .map(_.isDefault)
       .update(false)
 
-    Priorities
-      .filter(_.byPrimaryKey(owner, repository, priorityId))
+    priorityId.foreach(id => Priorities
+      .filter(_.byPrimaryKey(owner, repository, id))
       .map(_.isDefault)
-      .update(true)
+      .update(true))
   }
 }
diff --git a/src/main/scala/gitbucket/core/service/RepositoryCreationService.scala b/src/main/scala/gitbucket/core/service/RepositoryCreationService.scala
index 1fc487f..97df82d 100644
--- a/src/main/scala/gitbucket/core/service/RepositoryCreationService.scala
+++ b/src/main/scala/gitbucket/core/service/RepositoryCreationService.scala
@@ -84,6 +84,6 @@
     createPriority(userName, repositoryName, "important", "Issues can be shipped with a final product, but should be reviewed before the next release.", "fccd29")
     createPriority(userName, repositoryName, "default", "Default.", "acacac")
 
-    setDefaultPriority(userName, repositoryName, getPriority(userName, repositoryName, "default").get.priorityId)
+    setDefaultPriority(userName, repositoryName, getPriority(userName, repositoryName, "default").map(_.priorityId))
   }
 }
diff --git a/src/main/twirl/gitbucket/core/issues/priorities/list.scala.html b/src/main/twirl/gitbucket/core/issues/priorities/list.scala.html
index e53f24c..185ba84 100644
--- a/src/main/twirl/gitbucket/core/issues/priorities/list.scala.html
+++ b/src/main/twirl/gitbucket/core/issues/priorities/list.scala.html
@@ -103,11 +103,21 @@
 }
 
 function setDefaultPriority(priorityId){
+  var $a = $('a[data-id="' + priorityId + '"].priority-default');
+  var isDefault = $a.data('default');
   $.post('@helpers.url(repository)/issues/priorities/default',
-    { priorityId: priorityId },
+    { priorityId: isDefault ? '' : priorityId },
     function(){
-      $('.priority-default').removeClass('priority-default-selected');
-      $('a[data-id="' + priorityId + '"] .priority-default').addClass('priority-default-selected');
+      $('.priority-default')
+        .removeClass('priority-default-selected')
+        .data('default', false)
+        .attr('title', 'Set as default');
+      if (!isDefault) {
+        $a
+          .addClass('priority-default-selected')
+          .data('default', true)
+          .attr('title', 'Unset as default');
+      }
     }
   );
 }
diff --git a/src/main/twirl/gitbucket/core/issues/priorities/priority.scala.html b/src/main/twirl/gitbucket/core/issues/priorities/priority.scala.html
index b9e1ad1..637b11a 100644
--- a/src/main/twirl/gitbucket/core/issues/priorities/priority.scala.html
+++ b/src/main/twirl/gitbucket/core/issues/priorities/priority.scala.html
@@ -24,7 +24,7 @@
       <div class="col-md-1">
         <div class="pull-right">
           @if(hasWritePermission){
-            <a href="javascript:void(0);" onclick="setDefaultPriority(@priority.priorityId)" data-id="@priority.priorityId"><i class="octicon octicon-star priority-default@if(priority.isDefault){ priority-default-selected}" title="@if(priority.isDefault){Default} else {Set as default}"></i></a>
+            <a href="javascript:void(0);" onclick="setDefaultPriority(@priority.priorityId)" data-id="@priority.priorityId" data-default="@priority.isDefault" class="priority-default@if(priority.isDefault){ priority-default-selected}" title="@if(priority.isDefault){Unset as default} else {Set as default}"><i class="octicon octicon-star"></i></a>
           } else if(priority.isDefault) {
             <i class="octicon octicon-star priority-default priority-default-selected" title="Default"></i>
           }
diff --git a/src/main/webapp/assets/common/css/gitbucket.css b/src/main/webapp/assets/common/css/gitbucket.css
index d653877..b02f030 100644
--- a/src/main/webapp/assets/common/css/gitbucket.css
+++ b/src/main/webapp/assets/common/css/gitbucket.css
@@ -965,12 +965,12 @@
   font-size: 2em;
 }
 
-.priority-default {
+.priority-default .octicon {
   font-size: 1.5em;
   color: #ccc;
 }
 
-.priority-default-selected {
+.priority-default-selected .octicon {
   color: #3c8dbc;
 }