diff --git a/src/journal/cat.c b/src/journal/cat.c
index 1634f30b44..90d4f5352f 100644
--- a/src/journal/cat.c
+++ b/src/journal/cat.c
@@ -95,10 +95,7 @@ static int parse_argv(int argc, char *argv[]) {
                         return version();
 
                 case 't':
-                        if (isempty(optarg))
-                                arg_identifier = NULL;
-                        else
-                                arg_identifier = optarg;
+                        arg_identifier = empty_to_null(optarg);
                         break;
 
                 case 'p':
@@ -122,10 +119,7 @@ static int parse_argv(int argc, char *argv[]) {
                         break;
 
                 case ARG_NAMESPACE:
-                        if (isempty(optarg))
-                                arg_namespace = NULL;
-                        else
-                                arg_namespace = optarg;
+                        arg_namespace = empty_to_null(optarg);
                         break;
 
                 case '?':