diff --git a/update_manager/update_manager_unittest.cc b/update_manager/update_manager_unittest.cc
index 4cc738d..03f1610 100644
--- a/update_manager/update_manager_unittest.cc
+++ b/update_manager/update_manager_unittest.cc
@@ -253,9 +253,9 @@
 
   umut_->AsyncPolicyRequest(callback, &Policy::UpdateCheckAllowed);
   // The callback should wait until we run the main loop for it to be executed.
-  EXPECT_EQ(0, calls.size());
+  EXPECT_EQ(0U, calls.size());
   MessageLoopRunMaxIterations(MessageLoop::current(), 100);
-  EXPECT_EQ(1, calls.size());
+  EXPECT_EQ(1U, calls.size());
 }
 
 TEST_F(UmUpdateManagerTest, AsyncPolicyRequestTimeoutDoesNotFire) {
@@ -273,14 +273,14 @@
   // to the default.
   MessageLoopRunMaxIterations(MessageLoop::current(), 100);
   EXPECT_EQ(1, num_called);
-  ASSERT_EQ(1, calls.size());
+  ASSERT_EQ(1U, calls.size());
   EXPECT_EQ(EvalStatus::kSucceeded, calls[0].first);
   // Wait for the timeout to expire, run the main loop again, ensure that
   // nothing happened.
   test_clock_.Advance(TimeDelta::FromSeconds(2));
   MessageLoopRunMaxIterations(MessageLoop::current(), 10);
   EXPECT_EQ(1, num_called);
-  EXPECT_EQ(1, calls.size());
+  EXPECT_EQ(1U, calls.size());
 }
 
 TEST_F(UmUpdateManagerTest, AsyncPolicyRequestTimesOut) {
@@ -301,7 +301,7 @@
   // was not invoked.
   MessageLoopRunMaxIterations(MessageLoop::current(), 100);
   EXPECT_EQ(1, num_called);
-  EXPECT_EQ(0, calls.size());
+  EXPECT_EQ(0U, calls.size());
   // Wait for the expiration timeout to expire, run the main loop again,
   // ensure that reevaluation occurred but callback was not invoked (i.e.
   // default policy was not consulted).
@@ -310,7 +310,7 @@
                                TimeDelta::FromSeconds(2));
   MessageLoopRunMaxIterations(MessageLoop::current(), 10);
   EXPECT_EQ(2, num_called);
-  EXPECT_EQ(0, calls.size());
+  EXPECT_EQ(0U, calls.size());
   // Wait for reevaluation due to delay to happen, ensure that it occurs and
   // that the callback is invoked.
   test_clock_.Advance(TimeDelta::FromSeconds(2));
@@ -318,7 +318,7 @@
                                TimeDelta::FromSeconds(2));
   MessageLoopRunMaxIterations(MessageLoop::current(), 10);
   EXPECT_EQ(3, num_called);
-  ASSERT_EQ(1, calls.size());
+  ASSERT_EQ(1U, calls.size());
   EXPECT_EQ(EvalStatus::kSucceeded, calls[0].first);
 }
 
diff --git a/update_manager/variable_unittest.cc b/update_manager/variable_unittest.cc
index 13cceb1..144002a 100644
--- a/update_manager/variable_unittest.cc
+++ b/update_manager/variable_unittest.cc
@@ -99,13 +99,13 @@
   DefaultVariable<int> var("var", kVariableModeAsync);
   BaseVariableObserver observer;
   var.AddObserver(&observer);
-  EXPECT_EQ(var.observer_list_.size(), 1);
+  EXPECT_EQ(1U, var.observer_list_.size());
   var.AddObserver(&observer);
-  EXPECT_EQ(var.observer_list_.size(), 1);
+  EXPECT_EQ(1U, var.observer_list_.size());
   var.RemoveObserver(&observer);
-  EXPECT_EQ(var.observer_list_.size(), 0);
+  EXPECT_EQ(0U, var.observer_list_.size());
   var.RemoveObserver(&observer);
-  EXPECT_EQ(var.observer_list_.size(), 0);
+  EXPECT_EQ(0U, var.observer_list_.size());
 }
 
 TEST_F(UmBaseVariableTest, NotifyValueChangedTest) {
@@ -114,10 +114,10 @@
   var.AddObserver(&observer1);
   // Simulate a value change on the variable's implementation.
   var.NotifyValueChanged();
-  ASSERT_EQ(0, observer1.calls_.size());
+  ASSERT_EQ(0U, observer1.calls_.size());
   MessageLoopRunMaxIterations(MessageLoop::current(), 100);
 
-  ASSERT_EQ(1, observer1.calls_.size());
+  ASSERT_EQ(1U, observer1.calls_.size());
   // Check that the observer is called with the right argument.
   EXPECT_EQ(&var, observer1.calls_[0]);
 
@@ -127,8 +127,8 @@
   MessageLoopRunMaxIterations(MessageLoop::current(), 100);
 
   // Check that all the observers are called.
-  EXPECT_EQ(2, observer1.calls_.size());
-  EXPECT_EQ(1, observer2.calls_.size());
+  EXPECT_EQ(2U, observer1.calls_.size());
+  EXPECT_EQ(1U, observer2.calls_.size());
 
   var.RemoveObserver(&observer1);
   var.RemoveObserver(&observer2);