diff --git a/src/TransitionBuilder.vala b/lib/TransitionBuilder.vala
similarity index 100%
rename from src/TransitionBuilder.vala
rename to lib/TransitionBuilder.vala
diff --git a/lib/meson.build b/lib/meson.build
index cd54183cf..538f2af23 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -8,6 +8,7 @@ gala_lib_sources = files(
     'DragDropAction.vala',
     'Plugin.vala',
     'SessionSettings.vala',
+    'TransitionBuilder.vala',
     'Utils.vala',
     'WindowManager.vala',
     'AppSystem/App.vala',
diff --git a/src/meson.build b/src/meson.build
index b8887b80f..c6bd9d9ca 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -4,7 +4,6 @@ gala_bin_sources = files(
     'Main.vala',
     'PantheonShell.vala',
     'SuperScrollAction.vala',
-    'TransitionBuilder.vala',
     'WindowListModel.vala',
     'WindowManager.vala',
     'Background/Animation.vala',