diff --git a/src/components/views/rooms/SendMessageComposer.js b/src/components/views/rooms/SendMessageComposer.js
index 0e03d83467..b6d9c42707 100644
--- a/src/components/views/rooms/SendMessageComposer.js
+++ b/src/components/views/rooms/SendMessageComposer.js
@@ -290,11 +290,12 @@ export default class SendMessageComposer extends React.Component {
         const member = this.props.room.getMember(userId);
         const displayName = member ?
             member.rawDisplayName : userId;
-        const userPillPart = partCreator.userPill(displayName, userId);
         const caret = this._editorRef.getCaret();
         const position = model.positionForOffset(caret.offset, caret.atNodeEnd);
+        const insertIndex = position.index + 1;
+        const parts = partCreator.createMentionParts(insertIndex, displayName, userId);
         model.transform(() => {
-            const addedLen = model.insert([userPillPart], position);
+            const addedLen = model.insert(parts, position);
             return model.positionForOffset(caret.offset + addedLen, true);
         });
         // refocus on composer, as we just clicked "Mention"
diff --git a/src/editor/autocomplete.js b/src/editor/autocomplete.js
index fe6f3bfe1f..beb155f297 100644
--- a/src/editor/autocomplete.js
+++ b/src/editor/autocomplete.js
@@ -106,9 +106,7 @@ export default class AutocompleteWrapperModel {
                 if (completionId === "@room") {
                     return [this._partCreator.atRoomPill(completionId)];
                 } else {
-                    const pill = this._partCreator.userPill(text, completionId);
-                    const postfix = this._partCreator.plain(this._partIndex === 0 ? ": " : " ");
-                    return [pill, postfix];
+                    return this._partCreator.createMentionParts(this._partIndex, text, completionId);
                 }
             }
             case "#":
diff --git a/src/editor/parts.js b/src/editor/parts.js
index 9ca9205bcd..c10392bfd2 100644
--- a/src/editor/parts.js
+++ b/src/editor/parts.js
@@ -441,6 +441,12 @@ export class PartCreator {
         const member = this._room.getMember(userId);
         return new UserPillPart(userId, displayName, member);
     }
+
+    createMentionParts(partIndex, displayName, userId) {
+        const pill = this.userPill(displayName, userId);
+        const postfix = this.plain(partIndex === 0 ? ": " : " ");
+        return [pill, postfix];
+    }
 }
 
 // part creator that support auto complete for /commands,