1 files changed, 2 insertions, 0 deletions
diff --git a/src/core/transaction.c b/src/core/transaction.c
index c3d6ffccc1..65a00bd928 100644
--- a/src/core/transaction.c
+++ b/src/core/transaction.c
@@ -325,6 +325,8 @@ static char* merge_unit_ids(const char* unit_log_field, char * const* pairs) {
         _cleanup_free_ char *ans = NULL;
         size_t size = 0;
 
+        assert(unit_log_field);
+
         STRV_FOREACH_PAIR(unit_id, job_type, pairs) {
                 size_t next;