diff -u /Users/john/Development/Gnucash-Build/Gnucash-3/src/libchipcard-5.1.5rc2/src/tools/usbtan-test/main.c\~ /Users/john/Development/Gnucash-Build/Gnucash-3/src/libchipcard-5.1.5rc2/src/tools/usbtan-test/main.c
--- a/src/tools/usbtan-test/main.c	2020-01-12 08:22:44.000000000 -0800
+++ b/src/tools/usbtan-test/main.c	2020-03-07 10:31:29.000000000 -0800
@@ -12,6 +12,7 @@
 # include <config.h>
 #endif
 
+#include <ctype.h>
 #include <gwenhywfar/args.h>
 #include <gwenhywfar/cgui.h>
 #include <gwenhywfar/text.h>

Diff finished.  Sat Mar  7 11:14:03 2020