diff --git a/sys/src/ape/lib/fmt/dofmt.c b/sys/src/ape/lib/fmt/dofmt.c
index 3422e62cd..a3b42ae7a 100644
--- a/sys/src/ape/lib/fmt/dofmt.c
+++ b/sys/src/ape/lib/fmt/dofmt.c
@@ -544,7 +544,7 @@ __flagfmt(Fmt *f)
 		break;
 	case 'z':
 		f->flags |= FmtLong;
-		if(sizeof(void*) == sizeof(vlong))
+		if(sizeof(size_t) == sizeof(vlong))
 			f->flags |= FmtVLong;
 		break;
 	}
diff --git a/sys/src/ape/lib/fmt/test.c b/sys/src/ape/lib/fmt/test.c
index 3d082a816..b968d726d 100644
--- a/sys/src/ape/lib/fmt/test.c
+++ b/sys/src/ape/lib/fmt/test.c
@@ -12,6 +12,7 @@
  * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
  */
 #include <stdarg.h>
+#include <stddef.h>
 #include <utf.h>
 #include "fmt.h"
 
@@ -36,6 +37,6 @@ main(int argc, char *argv[])
 	print("%d\n", 23);
 	print("%i\n", 23);
 	print("%p\n", argv);
-	print("%zd\n", &argv[1] - &argv[0]);
+	print("%zd\n", (size_t)-1);
 	return 0;
 }