diff --git a/time.c b/time.c
index 617326f9961647..d0c1d0811e1804 100644
--- a/time.c
+++ b/time.c
@@ -4410,7 +4410,7 @@ time_plus(VALUE time1, VALUE time2)
  *
  *  When +other_time+ is given,
  *  returns a Float whose value is the difference
- *  of the numeric values of +self+ and +other_time+:
+ *  of the numeric values of +self+ and +other_time+ in seconds:
  *
  *    t - t # => 0.0
  *