diff --git a/src/components/views/rooms/BasicMessageComposer.tsx b/src/components/views/rooms/BasicMessageComposer.tsx
index a8a33af867..31651d807d 100644
--- a/src/components/views/rooms/BasicMessageComposer.tsx
+++ b/src/components/views/rooms/BasicMessageComposer.tsx
@@ -726,9 +726,8 @@ export default class BasicMessageEditor extends React.Component<IProps, IState>
             member.rawDisplayName : userId;
         const caret = this.getCaret();
         const position = model.positionForOffset(caret.offset, caret.atNodeEnd);
-        // index is -1 if there are no parts but we only care for if this would be the part in position 0
-        const insertIndex = position.index > 0 ? position.index : 0;
-        const parts = partCreator.createMentionParts(insertIndex, displayName, userId);
+        // Insert suffix only if the caret is at the start of the composer
+        const parts = partCreator.createMentionParts(caret.offset === 0, displayName, userId);
         model.transform(() => {
             const addedLen = model.insert(parts, position);
             return model.positionForOffset(caret.offset + addedLen, true);