diff --git a/activemodel/lib/active_model/type/helpers/time_value.rb b/activemodel/lib/active_model/type/helpers/time_value.rb
index ad78fd49ec..721f9543ed 100644
--- a/activemodel/lib/active_model/type/helpers/time_value.rb
+++ b/activemodel/lib/active_model/type/helpers/time_value.rb
@@ -34,7 +34,7 @@ def apply_seconds_precision(value)
           return value unless precision && value.respond_to?(:usec)
           number_of_insignificant_digits = 6 - precision
           round_power = 10**number_of_insignificant_digits
-          value.change(usec: value.usec / round_power * round_power)
+          value.change(usec: value.usec - value.usec % round_power)
         end
 
         def type_cast_for_schema(value)