diff --git a/libevmasm/Assembly.cpp b/libevmasm/Assembly.cpp
index acf655c82..2978fdcdb 100644
--- a/libevmasm/Assembly.cpp
+++ b/libevmasm/Assembly.cpp
@@ -200,7 +200,7 @@ string Assembly::assemblyString(StringMap const& _sourceCodes) const
 
 Json::Value Assembly::createJsonValue(string _name, int _source, int _begin, int _end, string _value, string _jumpType)
 {
-	Json::Value value;
+	Json::Value value{Json::objectValue};
 	value["name"] = _name;
 	value["source"] = _source;
 	value["begin"] = _begin;
@@ -222,8 +222,9 @@ string Assembly::toStringInHex(u256 _value)
 Json::Value Assembly::assemblyJSON(map<string, unsigned> const& _sourceIndices) const
 {
 	Json::Value root;
+	root[".code"] = Json::arrayValue;
 
-	Json::Value& collection = root[".code"] = Json::arrayValue;
+	Json::Value& collection = root[".code"];
 	for (AssemblyItem const& i: m_items)
 	{
 		int sourceIndex = -1;
@@ -317,7 +318,8 @@ Json::Value Assembly::assemblyJSON(map<string, unsigned> const& _sourceIndices)
 
 	if (!m_data.empty() || !m_subs.empty())
 	{
-		Json::Value& data = root[".data"] = Json::objectValue;
+		root[".data"] = Json::objectValue;
+		Json::Value& data = root[".data"];
 		for (auto const& i: m_data)
 			if (u256(i.first) >= m_subs.size())
 				data[toStringInHex((u256)i.first)] = toHex(i.second);
diff --git a/libsolidity/interface/ABI.cpp b/libsolidity/interface/ABI.cpp
index c4a2dfe5c..cf395ffa0 100644
--- a/libsolidity/interface/ABI.cpp
+++ b/libsolidity/interface/ABI.cpp
@@ -56,7 +56,7 @@ Json::Value ABI::generate(ContractDefinition const& _contractDef)
 
 		FunctionType const* externalFunctionType = it.second->interfaceFunctionType();
 		solAssert(!!externalFunctionType, "");
-		Json::Value method;
+		Json::Value method{Json::objectValue};
 		method["type"] = "function";
 		method["name"] = it.second->declaration().name();
 		method["stateMutability"] = stateMutabilityToString(externalFunctionType->stateMutability());
@@ -80,7 +80,7 @@ Json::Value ABI::generate(ContractDefinition const& _contractDef)
 		FunctionType constrType(*constructor);
 		FunctionType const* externalFunctionType = constrType.interfaceFunctionType();
 		solAssert(!!externalFunctionType, "");
-		Json::Value method;
+		Json::Value method{Json::objectValue};
 		method["type"] = "constructor";
 		method["stateMutability"] = stateMutabilityToString(externalFunctionType->stateMutability());
 		method["inputs"] = formatTypeList(
@@ -96,23 +96,22 @@ Json::Value ABI::generate(ContractDefinition const& _contractDef)
 		{
 			auto const* externalFunctionType = FunctionType(*fallbackOrReceive).interfaceFunctionType();
 			solAssert(!!externalFunctionType, "");
-			Json::Value method;
+			Json::Value method{Json::objectValue};
 			method["type"] = TokenTraits::toString(fallbackOrReceive->kind());
 			method["stateMutability"] = stateMutabilityToString(externalFunctionType->stateMutability());
 			abi.emplace(std::move(method));
 		}
 	for (auto const& it: _contractDef.interfaceEvents())
 	{
-		Json::Value event;
+		Json::Value event{Json::objectValue};
 		event["type"] = "event";
 		event["name"] = it->name();
 		event["anonymous"] = it->isAnonymous();
-		Json::Value params(Json::arrayValue);
+		Json::Value params{Json::arrayValue};
 		for (auto const& p: it->parameters())
 		{
 			Type const* type = p->annotation().type->interfaceType(false);
 			solAssert(type, "");
-			Json::Value input;
 			auto param = formatType(p->name(), *type, *p->annotation().type, false);
 			param["indexed"] = p->isIndexed();
 			params.append(std::move(param));
@@ -123,7 +122,7 @@ Json::Value ABI::generate(ContractDefinition const& _contractDef)
 
 	for (ErrorDefinition const* error: _contractDef.interfaceErrors())
 	{
-		Json::Value errorJson;
+		Json::Value errorJson{Json::objectValue};
 		errorJson["type"] = "error";
 		errorJson["name"] = error->name();
 		errorJson["inputs"] = Json::arrayValue;
@@ -151,7 +150,7 @@ Json::Value ABI::formatTypeList(
 	bool _forLibrary
 )
 {
-	Json::Value params(Json::arrayValue);
+	Json::Value params{Json::arrayValue};
 	solAssert(_names.size() == _encodingTypes.size(), "Names and types vector size does not match");
 	solAssert(_names.size() == _solidityTypes.size(), "");
 	for (unsigned i = 0; i < _names.size(); ++i)
@@ -169,7 +168,7 @@ Json::Value ABI::formatType(
 	bool _forLibrary
 )
 {
-	Json::Value ret;
+	Json::Value ret{Json::objectValue};
 	ret["name"] = _name;
 	ret["internalType"] = _solidityType.toString(true);
 	string suffix = (_forLibrary && _encodingType.dataStoredIn(DataLocation::Storage)) ? " storage" : "";
diff --git a/libsolidity/interface/CompilerStack.cpp b/libsolidity/interface/CompilerStack.cpp
index 3b5fb8cb5..c08ba6607 100644
--- a/libsolidity/interface/CompilerStack.cpp
+++ b/libsolidity/interface/CompilerStack.cpp
@@ -1429,7 +1429,7 @@ CompilerStack::Source const& CompilerStack::source(string const& _sourceName) co
 
 string CompilerStack::createMetadata(Contract const& _contract, bool _forIR) const
 {
-	Json::Value meta;
+	Json::Value meta{Json::objectValue};
 	meta["version"] = 1;
 	meta["language"] = m_importedSources ? "SolidityAST" : "Solidity";
 	meta["compiler"]["version"] = VersionStringStrict;
diff --git a/libsolidity/interface/Natspec.cpp b/libsolidity/interface/Natspec.cpp
index 402d8e15c..533cbaa3d 100644
--- a/libsolidity/interface/Natspec.cpp
+++ b/libsolidity/interface/Natspec.cpp
@@ -37,7 +37,7 @@ using namespace solidity::frontend;
 
 Json::Value Natspec::userDocumentation(ContractDefinition const& _contractDef)
 {
-	Json::Value doc;
+	Json::Value doc{Json::objectValue};
 
 	doc["version"] = Json::Value(c_natspecVersion);
 	doc["kind"]    = Json::Value("user");
@@ -50,7 +50,7 @@ Json::Value Natspec::userDocumentation(ContractDefinition const& _contractDef)
 		if (!value.empty())
 		{
 			// add the constructor, only if we have any documentation to add
-			Json::Value user;
+			Json::Value user{Json::objectValue};
 			user["notice"] = Json::Value(value);
 			doc["methods"]["constructor"] = user;
 		}
@@ -90,7 +90,7 @@ Json::Value Natspec::userDocumentation(ContractDefinition const& _contractDef)
 		string value = extractDoc(error->annotation().docTags, "notice");
 		if (!value.empty())
 		{
-			Json::Value errorDoc;
+			Json::Value errorDoc{Json::objectValue};
 			errorDoc["notice"] = value;
 			doc["errors"][error->functionType(true)->externalSignature()].append(move(errorDoc));
 		}
@@ -225,7 +225,10 @@ Json::Value Natspec::extractCustomDoc(multimap<string, DocTag> const& _tags)
 	for (auto const& [tag, value]: _tags)
 		if (boost::starts_with(tag, "custom"))
 			concatenated[tag] += value.content;
-	Json::Value result;
+	// We do not want to create an object if there are no custom tags found.
+	if (concatenated.empty())
+		return Json::nullValue;
+	Json::Value result{Json::objectValue};
 	for (auto& [tag, value]: concatenated)
 		result[tag] = move(value);
 	return result;
diff --git a/libsolidity/interface/StandardCompiler.cpp b/libsolidity/interface/StandardCompiler.cpp
index 1031ec7c3..7d354a405 100644
--- a/libsolidity/interface/StandardCompiler.cpp
+++ b/libsolidity/interface/StandardCompiler.cpp
@@ -59,7 +59,7 @@ Json::Value formatError(
 	Json::Value const& _secondarySourceLocation = Json::Value()
 )
 {
-	Json::Value error = Json::objectValue;
+	Json::Value error{Json::objectValue};
 	error["type"] = _type;
 	error["component"] = _component;
 	error["severity"] = Error::formatErrorSeverityLowercase(_severity);
@@ -74,7 +74,7 @@ Json::Value formatError(
 
 Json::Value formatFatalError(string const& _type, string const& _message)
 {
-	Json::Value output = Json::objectValue;
+	Json::Value output{Json::objectValue};
 	output["errors"] = Json::arrayValue;
 	output["errors"].append(formatError(Error::Severity::Error, _type, "general", _message));
 	return output;
@@ -82,23 +82,22 @@ Json::Value formatFatalError(string const& _type, string const& _message)
 
 Json::Value formatSourceLocation(SourceLocation const* location)
 {
-	Json::Value sourceLocation;
-	if (location && location->sourceName)
-	{
-		sourceLocation["file"] = *location->sourceName;
-		sourceLocation["start"] = location->start;
-		sourceLocation["end"] = location->end;
-	}
+	if (!location || !location->sourceName)
+		return Json::nullValue;
 
+	Json::Value sourceLocation{Json::objectValue};
+	sourceLocation["file"] = *location->sourceName;
+	sourceLocation["start"] = location->start;
+	sourceLocation["end"] = location->end;
 	return sourceLocation;
 }
 
 Json::Value formatSecondarySourceLocation(SecondarySourceLocation const* _secondaryLocation)
 {
 	if (!_secondaryLocation)
-		return {};
+		return Json::nullValue;
 
-	Json::Value secondarySourceLocation = Json::arrayValue;
+	Json::Value secondarySourceLocation{Json::arrayValue};
 	for (auto const& location: _secondaryLocation->infos)
 	{
 		Json::Value msg = formatSourceLocation(&location.second);
@@ -330,7 +329,7 @@ bool isIRRequested(Json::Value const& _outputSelection)
 
 Json::Value formatLinkReferences(std::map<size_t, std::string> const& linkReferences)
 {
-	Json::Value ret(Json::objectValue);
+	Json::Value ret{Json::objectValue};
 
 	for (auto const& ref: linkReferences)
 	{
@@ -345,7 +344,7 @@ Json::Value formatLinkReferences(std::map<size_t, std::string> const& linkRefere
 		Json::Value fileObject = ret.get(file, Json::objectValue);
 		Json::Value libraryArray = fileObject.get(name, Json::arrayValue);
 
-		Json::Value entry = Json::objectValue;
+		Json::Value entry{Json::objectValue};
 		entry["start"] = Json::UInt(ref.first);
 		entry["length"] = 20;
 
@@ -359,7 +358,7 @@ Json::Value formatLinkReferences(std::map<size_t, std::string> const& linkRefere
 
 Json::Value formatImmutableReferences(map<u256, pair<string, vector<size_t>>> const& _immutableReferences)
 {
-	Json::Value ret(Json::objectValue);
+	Json::Value ret{Json::objectValue};
 
 	for (auto const& immutableReference: _immutableReferences)
 	{
@@ -367,7 +366,7 @@ Json::Value formatImmutableReferences(map<u256, pair<string, vector<size_t>>> co
 		Json::Value array(Json::arrayValue);
 		for (size_t byteOffset: byteOffsets)
 		{
-			Json::Value byteRange(Json::objectValue);
+			Json::Value byteRange{Json::objectValue};
 			byteRange["start"] = Json::UInt(byteOffset);
 			byteRange["length"] = Json::UInt(32); // immutable references are currently always 32 bytes wide
 			array.append(byteRange);
@@ -386,7 +385,7 @@ Json::Value collectEVMObject(
 	function<bool(string)> const& _artifactRequested
 )
 {
-	Json::Value output = Json::objectValue;
+	Json::Value output{Json::objectValue};
 	if (_artifactRequested("object"))
 		output["object"] = _object.toHex();
 	if (_artifactRequested("opcodes"))