diff --git a/core/src/detail/hash.h b/core/src/detail/hash.h
index 0198554d..58694de3 100644
--- a/core/src/detail/hash.h
+++ b/core/src/detail/hash.h
@@ -11,7 +11,7 @@ namespace detail {
 /// It's the boundary condition of this serial functions.
 ///
 /// \param seed Not effect.
-inline void hash_combine(std::size_t *seed) {}
+inline void hash_combine(std::size_t */*seed*/) {}
 
 /// \brief Combine the given hash value with another obeject.
 ///
diff --git a/core/tests/family_test.cc b/core/tests/family_test.cc
index f26b16e1..455ad627 100644
--- a/core/tests/family_test.cc
+++ b/core/tests/family_test.cc
@@ -20,8 +20,8 @@ TEST(FamilyTest, labels) {
                          {{const_label.name, const_label.value}}};
   family.Add({{dynamic_label.name, dynamic_label.value}});
   auto collected = family.Collect();
-  ASSERT_GE(collected.size(), 1);
-  ASSERT_GE(collected.at(0).metric.size(), 1);
+  ASSERT_GE(collected.size(), 1U);
+  ASSERT_GE(collected.at(0).metric.size(), 1U);
   EXPECT_THAT(collected.at(0).metric.at(0).label,
               ::testing::ElementsAre(const_label, dynamic_label));
 }
@@ -31,8 +31,8 @@ TEST(FamilyTest, counter_value) {
   auto& counter = family.Add({});
   counter.Increment();
   auto collected = family.Collect();
-  ASSERT_GE(collected.size(), 1);
-  ASSERT_GE(collected[0].metric.size(), 1);
+  ASSERT_GE(collected.size(), 1U);
+  ASSERT_GE(collected[0].metric.size(), 1U);
   EXPECT_EQ(1, collected[0].metric.at(0).counter.value);
 }
 
@@ -42,8 +42,8 @@ TEST(FamilyTest, remove) {
   family.Add({{"name", "counter2"}});
   family.Remove(&counter1);
   auto collected = family.Collect();
-  ASSERT_GE(collected.size(), 1);
-  EXPECT_EQ(collected[0].metric.size(), 1);
+  ASSERT_GE(collected.size(), 1U);
+  EXPECT_EQ(collected[0].metric.size(), 1U);
 }
 
 TEST(FamilyTest, Histogram) {
@@ -52,9 +52,9 @@ TEST(FamilyTest, Histogram) {
                                 Histogram::BucketBoundaries{0, 1, 2});
   histogram1.Observe(0);
   auto collected = family.Collect();
-  ASSERT_EQ(collected.size(), 1);
-  ASSERT_GE(collected[0].metric.size(), 1);
-  EXPECT_EQ(1, collected[0].metric.at(0).histogram.sample_count);
+  ASSERT_EQ(collected.size(), 1U);
+  ASSERT_GE(collected[0].metric.size(), 1U);
+  EXPECT_EQ(1U, collected[0].metric.at(0).histogram.sample_count);
 }
 
 TEST(FamilyTest, add_twice) {
diff --git a/core/tests/histogram_test.cc b/core/tests/histogram_test.cc
index 1ef26bd2..60aa75fb 100644
--- a/core/tests/histogram_test.cc
+++ b/core/tests/histogram_test.cc
@@ -11,7 +11,7 @@ TEST(HistogramTest, initialize_with_zero) {
   Histogram histogram{{}};
   auto metric = histogram.Collect();
   auto h = metric.histogram;
-  EXPECT_EQ(h.sample_count, 0);
+  EXPECT_EQ(h.sample_count, 0U);
   EXPECT_EQ(h.sample_sum, 0);
 }
 
@@ -21,7 +21,7 @@ TEST(HistogramTest, sample_count) {
   histogram.Observe(200);
   auto metric = histogram.Collect();
   auto h = metric.histogram;
-  EXPECT_EQ(h.sample_count, 2);
+  EXPECT_EQ(h.sample_count, 2U);
 }
 
 TEST(HistogramTest, sample_sum) {
@@ -38,7 +38,7 @@ TEST(HistogramTest, bucket_size) {
   Histogram histogram{{1, 2}};
   auto metric = histogram.Collect();
   auto h = metric.histogram;
-  EXPECT_EQ(h.bucket.size(), 3);
+  EXPECT_EQ(h.bucket.size(), 3U);
 }
 
 TEST(HistogramTest, bucket_bounds) {
@@ -58,8 +58,8 @@ TEST(HistogramTest, bucket_counts_not_reset_by_collection) {
   histogram.Observe(1.5);
   auto metric = histogram.Collect();
   auto h = metric.histogram;
-  ASSERT_EQ(h.bucket.size(), 3);
-  EXPECT_EQ(h.bucket.at(1).cumulative_count, 2);
+  ASSERT_EQ(h.bucket.size(), 3U);
+  EXPECT_EQ(h.bucket.at(1).cumulative_count, 2U);
 }
 
 TEST(HistogramTest, cumulative_bucket_count) {
@@ -73,10 +73,10 @@ TEST(HistogramTest, cumulative_bucket_count) {
   histogram.Observe(3);
   auto metric = histogram.Collect();
   auto h = metric.histogram;
-  ASSERT_EQ(h.bucket.size(), 3);
-  EXPECT_EQ(h.bucket.at(0).cumulative_count, 3);
-  EXPECT_EQ(h.bucket.at(1).cumulative_count, 6);
-  EXPECT_EQ(h.bucket.at(2).cumulative_count, 7);
+  ASSERT_EQ(h.bucket.size(), 3U);
+  EXPECT_EQ(h.bucket.at(0).cumulative_count, 3U);
+  EXPECT_EQ(h.bucket.at(1).cumulative_count, 6U);
+  EXPECT_EQ(h.bucket.at(2).cumulative_count, 7U);
 }
 
 }  // namespace
diff --git a/core/tests/registry_test.cc b/core/tests/registry_test.cc
index ee0b7d50..6c6ecc68 100644
--- a/core/tests/registry_test.cc
+++ b/core/tests/registry_test.cc
@@ -16,13 +16,13 @@ TEST(RegistryTest, collect_single_metric_family) {
   counter_family.Add({{"name", "counter1"}});
   counter_family.Add({{"name", "counter2"}});
   auto collected = registry.Collect();
-  ASSERT_EQ(collected.size(), 1);
+  ASSERT_EQ(collected.size(), 1U);
   EXPECT_EQ(collected[0].name, "test");
   EXPECT_EQ(collected[0].help, "a test");
-  ASSERT_EQ(collected[0].metric.size(), 2);
-  ASSERT_EQ(collected[0].metric.at(0).label.size(), 1);
+  ASSERT_EQ(collected[0].metric.size(), 2U);
+  ASSERT_EQ(collected[0].metric.at(0).label.size(), 1U);
   EXPECT_EQ(collected[0].metric.at(0).label.at(0).name, "name");
-  ASSERT_EQ(collected[0].metric.at(1).label.size(), 1);
+  ASSERT_EQ(collected[0].metric.at(1).label.size(), 1U);
   EXPECT_EQ(collected[0].metric.at(1).label.at(0).name, "name");
 }
 
@@ -34,7 +34,7 @@ TEST(RegistryTest, build_histogram_family) {
                                          Histogram::BucketBoundaries{0, 1, 2});
   histogram.Observe(1.1);
   auto collected = registry.Collect();
-  ASSERT_EQ(collected.size(), 1);
+  ASSERT_EQ(collected.size(), 1U);
 }
 
 }  // namespace
diff --git a/core/tests/summary_test.cc b/core/tests/summary_test.cc
index 44133794..243a4dee 100644
--- a/core/tests/summary_test.cc
+++ b/core/tests/summary_test.cc
@@ -12,7 +12,7 @@ TEST(SummaryTest, initialize_with_zero) {
   Summary summary{Summary::Quantiles{}};
   auto metric = summary.Collect();
   auto s = metric.summary;
-  EXPECT_EQ(s.sample_count, 0);
+  EXPECT_EQ(s.sample_count, 0U);
   EXPECT_EQ(s.sample_sum, 0);
 }
 
@@ -22,7 +22,7 @@ TEST(SummaryTest, sample_count) {
   summary.Observe(200);
   auto metric = summary.Collect();
   auto s = metric.summary;
-  EXPECT_EQ(s.sample_count, 2);
+  EXPECT_EQ(s.sample_count, 2U);
 }
 
 TEST(SummaryTest, sample_sum) {
@@ -39,14 +39,14 @@ TEST(SummaryTest, quantile_size) {
   Summary summary{Summary::Quantiles{{0.5, 0.05}, {0.90, 0.01}}};
   auto metric = summary.Collect();
   auto s = metric.summary;
-  EXPECT_EQ(s.quantile.size(), 2);
+  EXPECT_EQ(s.quantile.size(), 2U);
 }
 
 TEST(SummaryTest, quantile_bounds) {
   Summary summary{Summary::Quantiles{{0.5, 0.05}, {0.90, 0.01}, {0.99, 0.001}}};
   auto metric = summary.Collect();
   auto s = metric.summary;
-  ASSERT_EQ(s.quantile.size(), 3);
+  ASSERT_EQ(s.quantile.size(), 3U);
   EXPECT_DOUBLE_EQ(s.quantile.at(0).quantile, 0.5);
   EXPECT_DOUBLE_EQ(s.quantile.at(1).quantile, 0.9);
   EXPECT_DOUBLE_EQ(s.quantile.at(2).quantile, 0.99);
@@ -60,7 +60,7 @@ TEST(SummaryTest, quantile_values) {
 
   auto metric = summary.Collect();
   auto s = metric.summary;
-  ASSERT_EQ(s.quantile.size(), 3);
+  ASSERT_EQ(s.quantile.size(), 3U);
 
   EXPECT_NEAR(s.quantile.at(0).value, 0.5 * SAMPLES, 0.05 * SAMPLES);
   EXPECT_NEAR(s.quantile.at(1).value, 0.9 * SAMPLES, 0.01 * SAMPLES);
@@ -75,7 +75,7 @@ TEST(SummaryTest, max_age) {
   static const auto test_value = [&summary](double ref) {
     auto metric = summary.Collect();
     auto s = metric.summary;
-    ASSERT_EQ(s.quantile.size(), 1);
+    ASSERT_EQ(s.quantile.size(), 1U);
 
     if (std::isnan(ref))
       EXPECT_TRUE(std::isnan(s.quantile.at(0).value));
diff --git a/pull/src/handler.cc b/pull/src/handler.cc
index a81d7787..0a2e2676 100644
--- a/pull/src/handler.cc
+++ b/pull/src/handler.cc
@@ -113,7 +113,7 @@ static std::size_t WriteResponse(struct mg_connection* conn,
   return body.size();
 }
 
-bool MetricsHandler::handleGet(CivetServer* server,
+bool MetricsHandler::handleGet(CivetServer* /*server*/,
                                struct mg_connection* conn) {
   auto start_time_of_request = std::chrono::steady_clock::now();
 
diff --git a/pull/tests/integration/sample_server.cc b/pull/tests/integration/sample_server.cc
index e71091b1..998d27aa 100644
--- a/pull/tests/integration/sample_server.cc
+++ b/pull/tests/integration/sample_server.cc
@@ -7,7 +7,7 @@
 #include <prometheus/exposer.h>
 #include <prometheus/registry.h>
 
-int main(int argc, char** argv) {
+int main() {
   using namespace prometheus;
 
   // create an http server running on port 8080
diff --git a/push/tests/integration/sample_client.cc b/push/tests/integration/sample_client.cc
index aa8442f3..5c82070a 100644
--- a/push/tests/integration/sample_client.cc
+++ b/push/tests/integration/sample_client.cc
@@ -23,7 +23,7 @@ static std::string GetHostName() {
   return hostname;
 }
 
-int main(int argc, char** argv) {
+int main() {
   using namespace prometheus;
 
   // create a push gateway