diff --git a/src/config/kbdbind.c b/src/config/kbdbind.c
index c630c12c0..d8d597d8d 100644
--- a/src/config/kbdbind.c
+++ b/src/config/kbdbind.c
@@ -369,6 +369,9 @@ read_key(const unsigned char *key_str)
 	return KBD_UNDEF;
 }
 
+/* Parse the string @s as the name of a keystroke.
+ * Write the parsed key and modifiers to *@kbd.
+ * Return >=0 on success, <0 on error.  */
 int
 parse_keystroke(const unsigned char *s, struct term_event_keyboard *kbd)
 {