diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index 2c6d5e118ac1..f9e3aee6a211 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -115,6 +115,9 @@ static int textual_leaf_to_string(const u32 *block, char *buf, size_t size)
  *
  * The string is taken from a minimal ASCII text descriptor leaf after
  * the immediate entry with @key.  The string is zero-terminated.
+ * An overlong string is silently truncated such that it and the
+ * zero byte fit into @size.
+ *
  * Returns strlen(buf) or a negative error code.
  */
 int fw_csr_string(const u32 *directory, int key, char *buf, size_t size)