--- a/sys/libprop/prop_array_util.c
+++ b/sys/libprop/prop_array_util.c
@@ -184,7 +184,7 @@
 	prop_number_t num;						\
 	int rv;								\
 									\
-	num = prop_number_create_integer((int64_t) val);		\
+	num = prop_number_create_unsigned_integer((uint64_t) val);		\
 	if (num == NULL)						\
 		return (false);						\
 	rv = prop_array_add(array, num);				\