diff --git a/internal_packages/message-list/lib/message-item.cjsx b/internal_packages/message-list/lib/message-item.cjsx
index 09af7fc89..e54592cfe 100644
--- a/internal_packages/message-list/lib/message-item.cjsx
+++ b/internal_packages/message-list/lib/message-item.cjsx
@@ -125,10 +125,14 @@ class MessageItem extends React.Component
       isDetailed={@state.detailedHeaders} />
 
   _renderFolder: =>
-    return [] unless @state.detailedHeaders and @props.message.folder
+    return [] unless @state.detailedHeaders
+    acct = AccountStore.accountForId(@props.message.accountId)
+    acctUsesFolders = acct and acct.usesFolders()
+    folder = @props.message.categories?[0]
+    return unless folder and acctUsesFolders
     <div className="header-row">
       <div className="header-label">Folder:&nbsp;</div>
-      <div className="header-name">{@props.message.folder.displayName}</div>
+      <div className="header-name">{folder.displayName}</div>
     </div>
 
   _onClickParticipants: (e) =>
diff --git a/internal_packages/message-list/lib/message-list-hidden-messages-toggle.jsx b/internal_packages/message-list/lib/message-list-hidden-messages-toggle.jsx
index f8edbe8e1..91dbb60e9 100644
--- a/internal_packages/message-list/lib/message-list-hidden-messages-toggle.jsx
+++ b/internal_packages/message-list/lib/message-list-hidden-messages-toggle.jsx
@@ -31,7 +31,7 @@ export default class MessageListHiddenMessagesToggle extends React.Component {
   render() {
     const {numberOfHiddenItems} = this.state;
     if (numberOfHiddenItems === 0) {
-      return false;
+      return (<span />);
     }
 
 
diff --git a/spec/tasks/change-folder-task-spec.coffee b/spec/tasks/change-folder-task-spec.coffee
index 8257821d3..ecd2b6a35 100644
--- a/spec/tasks/change-folder-task-spec.coffee
+++ b/spec/tasks/change-folder-task-spec.coffee
@@ -133,12 +133,12 @@ describe "ChangeFolderTask", ->
 
       describe "changesToModel", ->
         describe "if the model is a Thread", ->
-          it "returns an object with a folders key, and an array with the folder", ->
-            expect(@task.changesToModel(@thread)).toEqual({folders: [testFolders['f1']]})
+          it "returns an object with a categories key, and an array with the folder", ->
+            expect(@task.changesToModel(@thread)).toEqual({categories: [testFolders['f1']]})
 
         describe "if the model is a Message", ->
-          it "returns an object with a folder key, and the folder", ->
-            expect(@task.changesToModel(@message)).toEqual({folder: testFolders['f1']})
+          it "returns an object with a categories key, and the folder", ->
+            expect(@task.changesToModel(@message)).toEqual({categories: [testFolders['f1']]})
 
       describe "requestBodyForModel", ->
         describe "if the model is a Thread", ->
@@ -149,10 +149,3 @@ describe "ChangeFolderTask", ->
             expect(@task.requestBodyForModel(@thread)).toEqual(folder: 'f1')
             @thread.folders = [testFolders['f2'], testFolders['f1']]
             expect(@task.requestBodyForModel(@thread)).toEqual(folder: 'f2')
-
-        describe "if the model is a Message", ->
-          it "returns folder: <id>, using the message folder", ->
-            @message.folder = null
-            expect(@task.requestBodyForModel(@message)).toEqual(folder: null)
-            @message.folder = testFolders['f1']
-            expect(@task.requestBodyForModel(@message)).toEqual(folder: 'f1')
diff --git a/src/components/mail-label-set.jsx b/src/components/mail-label-set.jsx
index 36723fd87..36646fef8 100644
--- a/src/components/mail-label-set.jsx
+++ b/src/components/mail-label-set.jsx
@@ -15,7 +15,7 @@ export default class MailLabelSet extends React.Component {
 
   static propTypes = {
     thread: React.PropTypes.object.isRequired,
-    includeCurrentCategories: React.PropTypes.boolean,
+    includeCurrentCategories: React.PropTypes.bool,
   };
 
   _onRemoveLabel(label) {
@@ -56,13 +56,14 @@ export default class MailLabelSet extends React.Component {
         labels.push(LabelComponentCache[label.id]);
       }
     }
-    return (<InjectedComponentSet
-      inline
-      containersRequired={false}
-      children={labels}
-      matching={{role: "Thread:MailLabel"}}
-      className="thread-injected-mail-labels"
-      exposedProps={{thread: thread}}/>
+    return (
+      <InjectedComponentSet
+        inline
+        containersRequired={false}
+        children={labels}
+        matching={{role: "Thread:MailLabel"}}
+        className="thread-injected-mail-labels"
+        exposedProps={{thread: thread}}/>
     );
   }
 }
diff --git a/src/flux/tasks/change-folder-task.coffee b/src/flux/tasks/change-folder-task.coffee
index 0d085f572..841c62307 100644
--- a/src/flux/tasks/change-folder-task.coffee
+++ b/src/flux/tasks/change-folder-task.coffee
@@ -81,9 +81,9 @@ class ChangeFolderTask extends ChangeMailTask
 
   changesToModel: (model) ->
     if model instanceof Thread
-      {folders: [@folder]}
+      {categories: [@folder]}
     else
-      {folder: @folder}
+      {categories: [@folder]}
 
   requestBodyForModel: (model) ->
     if model instanceof Thread