diff --git a/TODO b/TODO
index 78ccb86f..447e5f59 100644
--- a/TODO
+++ b/TODO
@@ -1,3 +1,12 @@
+- could add operator+= and friends to allow this
+
+	VImage im = ...;
+	VImage x = ...;
+
+	im += x;
+
+  unlike Python, C++ will not do this automatically
+
 - add more webp tests to py suite
 
 - try moving some more of the CLI tests to py