diff -u -r a/src/abstractaddin.cpp b/src/abstractaddin.cpp
--- a/src/abstractaddin.cpp	2021-03-10 22:27:51.581338702 +1100
+++ b/src/abstractaddin.cpp	2021-03-10 22:32:04.218679706 +1100
@@ -22,6 +22,7 @@
 
 
 #include "abstractaddin.hpp"
+#include <cstddef>
 
 namespace gnote {