diff --git a/lib/base/netstring.cpp b/lib/base/netstring.cpp
index 60f08c265..8f8fe4f67 100644
--- a/lib/base/netstring.cpp
+++ b/lib/base/netstring.cpp
@@ -167,7 +167,7 @@ String NetString::ReadStringFromStream(const Shared<AsioTlsStream>::Ptr& stream,
 		}
 	}
 
-	if (maxMessageLength >= 0 && len > maxMessageLength) {
+	if (maxMessageLength >= 0 && len > static_cast<std::size_t>(maxMessageLength)) {
 		std::stringstream errorMessage;
 		errorMessage << "Max data length exceeded: " << (maxMessageLength / 1024) << " KB";
 
@@ -246,7 +246,7 @@ String NetString::ReadStringFromStream(const Shared<AsioTlsStream>::Ptr& stream,
 		}
 	}
 
-	if (maxMessageLength >= 0 && len > maxMessageLength) {
+	if (maxMessageLength >= 0 && len > static_cast<std::size_t>(maxMessageLength)) {
 		std::stringstream errorMessage;
 		errorMessage << "Max data length exceeded: " << (maxMessageLength / 1024) << " KB";
 
diff --git a/lib/icingadb/icingadb-objects.cpp b/lib/icingadb/icingadb-objects.cpp
index 5c6443e84..4f21d05a0 100644
--- a/lib/icingadb/icingadb-objects.cpp
+++ b/lib/icingadb/icingadb-objects.cpp
@@ -549,7 +549,7 @@ std::vector<std::vector<intrusive_ptr<ConfigObject>>> IcingaDB::ChunkObjects(std
 
 	chunks.reserve((std::distance(offset, end) + chunkSize - 1) / chunkSize);
 
-	while (std::distance(offset, end) >= chunkSize) {
+	while (static_cast<std::size_t>(std::distance(offset, end)) >= chunkSize) {
 		auto until (offset + chunkSize);
 		chunks.emplace_back(offset, until);
 		offset = until;
diff --git a/lib/remote/apilistener-authority.cpp b/lib/remote/apilistener-authority.cpp
index e169ad4b1..4f55db44a 100644
--- a/lib/remote/apilistener-authority.cpp
+++ b/lib/remote/apilistener-authority.cpp
@@ -25,7 +25,7 @@ void ApiListener::UpdateObjectAuthority()
 
 	std::vector<Endpoint::Ptr> endpoints;
 	Endpoint::Ptr my_endpoint;
-	int hostChildrenInheritObjectAuthority = 0;
+	std::size_t hostChildrenInheritObjectAuthority = 0;
 
 	if (my_zone) {
 		my_endpoint = Endpoint::GetLocalEndpoint();
diff --git a/test/icinga-dependencies.cpp b/test/icinga-dependencies.cpp
index b1fbf7b4c..57a30e05f 100644
--- a/test/icinga-dependencies.cpp
+++ b/test/icinga-dependencies.cpp
@@ -35,7 +35,12 @@ static void RegisterDependency(Dependency::Ptr dep, const String& redundancyGrou
 	dep->GetParent()->AddReverseDependency(dep);
 }
 
-static void AssertCheckableRedundancyGroup(Checkable::Ptr checkable, int dependencyCount, int groupCount, int totalDependenciesCount)
+static void AssertCheckableRedundancyGroup(
+	Checkable::Ptr checkable,
+	std::size_t dependencyCount,
+	std::size_t groupCount,
+	std::size_t totalDependenciesCount
+)
 {
 	BOOST_CHECK_MESSAGE(
 		dependencyCount == checkable->GetDependencies().size(),
diff --git a/test/remote-httpserverconnection.cpp b/test/remote-httpserverconnection.cpp
index ac0f895b8..a2cb9ff2a 100644
--- a/test/remote-httpserverconnection.cpp
+++ b/test/remote-httpserverconnection.cpp
@@ -56,7 +56,7 @@ struct HttpServerConnectionFixture : TlsStreamFixture, ConfigurationCacheDirFixt
 	template<class Rep, class Period>
 	bool AssertServerDisconnected(const std::chrono::duration<Rep, Period>& timeout)
 	{
-		auto iterations = timeout / std::chrono::milliseconds(50);
+		std::size_t iterations = timeout / std::chrono::milliseconds(50);
 		for (std::size_t i = 0; i < iterations && !m_Connection->Disconnected(); i++) {
 			Utility::Sleep(std::chrono::duration<double>(timeout).count() / iterations);
 		}