diff --git a/src/libsystemd/sd-journal/journal-file.c b/src/libsystemd/sd-journal/journal-file.c
index c517e31cc4..d46d4914d4 100644
--- a/src/libsystemd/sd-journal/journal-file.c
+++ b/src/libsystemd/sd-journal/journal-file.c
@@ -2256,6 +2256,7 @@ int journal_file_append_entry(
         EntryItem *items;
         uint64_t xor_hash = 0;
         struct dual_timestamp _ts;
+        sd_id128_t _boot_id;
         int r;
 
         assert(f);
@@ -2277,6 +2278,14 @@ int journal_file_append_entry(
                 ts = &_ts;
         }
 
+        if (!boot_id) {
+                r = sd_id128_get_boot(&_boot_id);
+                if (r < 0)
+                        return r;
+
+                boot_id = &_boot_id;
+        }
+
 #if HAVE_GCRYPT
         r = journal_file_maybe_append_tag(f, ts->realtime);
         if (r < 0)