--- acinclude.m4
+++ acinclude.m4
@@ -212,7 +211,8 @@ done])dnl AC_CACHE_VAL
 LONG_LONG_INT_FORMAT=''
 
 case $pgac_cv_snprintf_long_long_int_format in
-  cross) AC_MSG_RESULT([cannot test (not on host machine)]);;
+  cross) AC_MSG_RESULT([assuming %lld for cross compilation])
+         LONG_LONG_INT_FORMAT='%lld';;
   ?*)    AC_MSG_RESULT([$pgac_cv_snprintf_long_long_int_format])
          LONG_LONG_INT_FORMAT=$pgac_cv_snprintf_long_long_int_format;;
   *)     AC_MSG_RESULT(none);;