diff --git a/src/libsystemd/sd-bus/bus-message.c b/src/libsystemd/sd-bus/bus-message.c
index 4005023d24..8a8fbde781 100644
--- a/src/libsystemd/sd-bus/bus-message.c
+++ b/src/libsystemd/sd-bus/bus-message.c
@@ -3159,7 +3159,8 @@ static struct bus_body_part* find_part(sd_bus_message *m, size_t index, size_t s
                                 return NULL;
 
                         if (p)
-                                *p = (uint8_t*) part->data + index - begin;
+                                *p = part->data ? (uint8_t*) part->data + index - begin
+                                        : NULL; /* Avoid dereferencing a NULL pointer. */
 
                         m->cached_rindex_part = part;
                         m->cached_rindex_part_begin = begin;
diff --git a/test/fuzz/fuzz-bus-message/zero-offset-to-null-pointer b/test/fuzz/fuzz-bus-message/zero-offset-to-null-pointer
new file mode 100644
index 0000000000..c1380441ed
Binary files /dev/null and b/test/fuzz/fuzz-bus-message/zero-offset-to-null-pointer differ