diff --git a/lib/clock.dart b/lib/clock.dart
index 640a20f..4ee971a 100644
--- a/lib/clock.dart
+++ b/lib/clock.dart
@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-part of quiver.time;
+import 'src/utils.dart';
 
 /// Returns current time.
 typedef DateTime TimeFunction();
diff --git a/lib/src/utils.dart b/lib/src/utils.dart
new file mode 100644
index 0000000..c4f11d0
--- /dev/null
+++ b/lib/src/utils.dart
@@ -0,0 +1,62 @@
+// Copyright 2018 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// This code is copied from quiver. We don't take on an explicit dependency
+// because quiver is very large and the amount of code we use from it is very
+// small.
+
+import 'package:meta/meta.dart';
+
+/// Days in a month. This array uses 1-based month numbers, i.e. January is
+/// the 1-st element in the array, not the 0-th.
+const _daysInMonth = const [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
+
+/// Returns the number of days in the specified month.
+///
+/// This function assumes the use of the Gregorian calendar or the proleptic
+/// Gregorian calendar.
+int daysInMonth(int year, int month) =>
+    (month == DateTime.FEBRUARY && isLeapYear(year)) ? 29 : _daysInMonth[month];
+
+/// Returns true if [year] is a leap year.
+///
+/// This implements the Gregorian calendar leap year rules wherein a year is
+/// considered to be a leap year if it is divisible by 4, excepting years
+/// divisible by 100, but including years divisible by 400.
+///
+/// This function assumes the use of the Gregorian calendar or the proleptic
+/// Gregorian calendar.
+bool isLeapYear(int year) =>
+    (year % 4 == 0) && ((year % 100 != 0) || (year % 400 == 0));
+
+/// Takes a [date] that may be outside the allowed range of dates for a given
+/// [month] in a given [year] and returns the closest date that is within the
+/// allowed range.
+///
+/// For example:
+///
+/// February 31, 2013 => February 28, 2013
+///
+/// When jumping from month to month or from leap year to common year we may
+/// end up in a month that has fewer days than the month we are jumping from.
+/// In that case it is impossible to preserve the exact date. So we "clamp" the
+/// date value to fit within the month. For example, jumping from March 31 one
+/// month back takes us to February 28 (or 29 during a leap year), as February
+/// doesn't have 31-st date.
+int clampDayOfMonth({
+  @required int year,
+  @required int month,
+  @required int day,
+}) =>
+    day.clamp(1, daysInMonth(year, month));
\ No newline at end of file
diff --git a/pubspec.yaml b/pubspec.yaml
index 52d25d2..5ebecf2 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -6,3 +6,9 @@
 
 environment:
   sdk: '>=1.24.0 <2.0.0'
+
+dependencies:
+  meta: '>=0.9.0 <2.0.0'
+
+dev_dependencies:
+  test: '^0.12.0'
diff --git a/test/clock_test.dart b/test/clock_test.dart
index 08c026a..7048c47 100644
--- a/test/clock_test.dart
+++ b/test/clock_test.dart
@@ -12,10 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-library quiver.time.clock_test;
+import 'package:clock/clock.dart';
 
 import 'package:test/test.dart';
-import 'package:quiver/time.dart';
 
 Clock from(int y, int m, int d) => new Clock.fixed(new DateTime(y, m, d));