diff --git a/ext/bigdecimal/bigdecimal.c b/ext/bigdecimal/bigdecimal.c
index 5821a0af20..c553e1d748 100644
--- a/ext/bigdecimal/bigdecimal.c
+++ b/ext/bigdecimal/bigdecimal.c
@@ -1636,7 +1636,8 @@ BigDecimal_divmod(VALUE self, VALUE r)
 }
 
 /*
- * See BigDecimal#quo
+ * Do the same manner as Float#div when n is nil.
+ * Do the same manner as BigDecimal#quo when n is 0.
  */
 static inline VALUE
 BigDecimal_div2(VALUE self, VALUE b, VALUE n)