diff --git a/lib/roken/snprintf.c b/lib/roken/snprintf.c
index db73ddc9f..3b6956024 100644
--- a/lib/roken/snprintf.c
+++ b/lib/roken/snprintf.c
@@ -435,6 +435,9 @@ xyzprintf (struct state *state, const char *char_format, va_list ap)
 	*arg = state->s - state->str;
 	break;
       }
+      case '\0' :
+	  --format;
+	  /* FALLTHROUGH */
       case '%' :
 	if ((*state->append_char)(state, c))
 	  return -1;