diff --git a/Plans---TODO.md b/Plans---TODO.md
index 79f779a..db8fa03 100644
--- a/Plans---TODO.md
+++ b/Plans---TODO.md
@@ -22,3 +22,4 @@ Everyone, please feel free to add new ideas or to add "clarification needed" to
 * make 16- and 32 bits per pixel mode work
 * teach executor to use multiple screens
 * make `DragWindow` and `GrowWindow` work properly with rootless window mode (the gray outline isn't visible where there is no window behind it)
+* run iwyu (include what you use) on the source files to clean up header file usage