diff --git a/lang/en.yml b/lang/en.yml
index 28aecf9f..bb9763f7 100644
--- a/lang/en.yml
+++ b/lang/en.yml
@@ -147,6 +147,7 @@ PREVIEW_CANCELLED: "Preview cancelled."
 PREVIEW_CANCELLING: "Cancelling preview..."
 PREVIEW_IN_GAME: "You can only preview rollbacks in-game."
 PREVIEW_TRANSACTION: "You can't preview {container|inventory} transactions."
+PRIMARY_THREAD_ERROR: "That API method can't be used on the primary thread."
 PURGE_ABORTED: "Purge failed. Database may be corrupt."
 PURGE_ERROR: "Unable to process {0} data!"
 PURGE_FAILED: "Purge failed. Please try again later."