diff --git a/builtin/apply.c b/builtin/apply.c
index deb1364fa81452d236a224109a99b28a034f9a9a..d61ac65dab28a766a13782bdef572431e20e80ff 100644
--- a/builtin/apply.c
+++ b/builtin/apply.c
@@ -4464,16 +4464,6 @@ static int option_parse_p(const struct option *opt,
 	return 0;
 }
 
-static int option_parse_z(const struct option *opt,
-			  const char *arg, int unset)
-{
-	if (unset)
-		line_termination = '\n';
-	else
-		line_termination = 0;
-	return 0;
-}
-
 static int option_parse_space_change(const struct option *opt,
 			  const char *arg, int unset)
 {
@@ -4546,9 +4536,9 @@ int cmd_apply(int argc, const char **argv, const char *prefix_)
 			 N_( "attempt three-way merge if a patch does not apply")),
 		OPT_FILENAME(0, "build-fake-ancestor", &fake_ancestor,
 			N_("build a temporary index based on embedded index information")),
-		{ OPTION_CALLBACK, 'z', NULL, NULL, NULL,
-			N_("paths are separated with NUL character"),
-			PARSE_OPT_NOARG, option_parse_z },
+		/* Think twice before adding "--nul" synonym to this */
+		OPT_SET_INT('z', NULL, &line_termination,
+			N_("paths are separated with NUL character"), '\0'),
 		OPT_INTEGER('C', NULL, &p_context,
 				N_("ensure at least <n> lines of context match")),
 		{ OPTION_CALLBACK, 0, "whitespace", &whitespace_option, N_("action"),
diff --git a/builtin/ls-files.c b/builtin/ls-files.c
index b6a7cb0c7c48293c6348806cb342a9289f146740..467699bcf5edad871784384cb6a5db178d0dc6d6 100644
--- a/builtin/ls-files.c
+++ b/builtin/ls-files.c
@@ -359,14 +359,6 @@ static const char * const ls_files_usage[] = {
 	NULL
 };
 
-static int option_parse_z(const struct option *opt,
-			  const char *arg, int unset)
-{
-	line_terminator = unset ? '\n' : '\0';
-
-	return 0;
-}
-
 static int option_parse_exclude(const struct option *opt,
 				const char *arg, int unset)
 {
@@ -408,9 +400,9 @@ int cmd_ls_files(int argc, const char **argv, const char *cmd_prefix)
 	struct exclude_list *el;
 	struct string_list exclude_list = STRING_LIST_INIT_NODUP;
 	struct option builtin_ls_files_options[] = {
-		{ OPTION_CALLBACK, 'z', NULL, NULL, NULL,
-			N_("paths are separated with NUL character"),
-			PARSE_OPT_NOARG, option_parse_z },
+		/* Think twice before adding "--nul" synonym to this */
+		OPT_SET_INT('z', NULL, &line_terminator,
+			N_("paths are separated with NUL character"), '\0'),
 		OPT_BOOL('t', NULL, &show_tag,
 			N_("identify the file status with tags")),
 		OPT_BOOL('v', NULL, &show_valid_bit,