--- freetype-2.10.4/src/truetype/ttgxvar.c	2020-08-27 08:17:20.000000000 +0200
+++ freetype-2.10.4/src/truetype/ttgxvar.c	2023-08-22 07:31:32.377121904 +0200
@@ -42,6 +42,7 @@
 #include <ft2build.h>
 #include <freetype/internal/ftdebug.h>
 #include FT_CONFIG_CONFIG_H
+#include <freetype/internal/ftcalc.h>
 #include <freetype/internal/ftstream.h>
 #include <freetype/internal/sfnt.h>
 #include <freetype/tttags.h>
@@ -1065,7 +1066,7 @@
                 delta == 1 ? "" : "s",
                 vertical ? "VVAR" : "HVAR" ));
 
-    *avalue += delta;
+    *avalue = ADD_INT( *avalue, delta );
 
   Exit:
     return error;