diff --git a/Meta/gn/secondary/Userland/Libraries/LibCore/BUILD.gn b/Meta/gn/secondary/Userland/Libraries/LibCore/BUILD.gn
index 986daa4dae..4aba55140d 100644
--- a/Meta/gn/secondary/Userland/Libraries/LibCore/BUILD.gn
+++ b/Meta/gn/secondary/Userland/Libraries/LibCore/BUILD.gn
@@ -72,6 +72,7 @@ source_set("sources") {
     "TCPServer.h",
     "ThreadEventQueue.cpp",
     "ThreadEventQueue.h",
+    "ThreadedPromise.h",
     "Timer.cpp",
     "Timer.h",
     "UDPServer.cpp",