diff --git a/pila.c b/pila.c
index f793aba..85c6c1b 100644
--- a/pila.c
+++ b/pila.c
@@ -463,8 +463,7 @@ read_number(Str ns, u64 *res)
 		n = n * 10 + cv;
 		++p;
 	}
-
-	if (p < pend)
+	if (p < pend) /* trailling characters, invalid number */
 		return false;
 
 	*res = n;