diff --git a/libgnucash/app-utils/gnc-option-uitype.hpp b/libgnucash/app-utils/gnc-option-uitype.hpp
index b33a4f95e8..ac3889f4ac 100644
--- a/libgnucash/app-utils/gnc-option-uitype.hpp
+++ b/libgnucash/app-utils/gnc-option-uitype.hpp
@@ -41,6 +41,7 @@ enum GncOptionUIType
     NUMBER_RANGE,
     COLOR,
     FONT,
+    PLOT_SIZE,
     BUDGET,
     PIXMAP,
     RADIOBUTTON,