diff --git a/include/plasp/pddl/expressions/Constant.h b/include/plasp/pddl/expressions/Constant.h
index ee4b83e..9864af0 100644
--- a/include/plasp/pddl/expressions/Constant.h
+++ b/include/plasp/pddl/expressions/Constant.h
@@ -28,8 +28,6 @@ class Constant: public Expression
 
 		static Constant *parseAndFind(Context &context, const ExpressionContext &expressionContext);
 
-		// TODO: method for lazy creation if not existing
-
 	public:
 		void accept(ExpressionVisitor &expressionVisitor) const override;
 
diff --git a/src/plasp/pddl/Domain.cpp b/src/plasp/pddl/Domain.cpp
index 4a8d7a3..0ea864b 100644
--- a/src/plasp/pddl/Domain.cpp
+++ b/src/plasp/pddl/Domain.cpp
@@ -184,7 +184,7 @@ void Domain::parseRequirementSection()
 		m_context.parser.skipWhiteSpace();
 	}
 
-	// TODO: Do this check only once the problem is parsed
+	// TODO: do this check only once the problem is parsed
 	// If no requirements are specified, assume STRIPS
 	if (m_requirements.empty())
 		m_requirements.emplace_back(Requirement::Type::STRIPS);
@@ -310,14 +310,6 @@ void Domain::parseActionSection()
 
 void Domain::checkConsistency()
 {
-	// Verify that all used predicates have been declared
-	std::for_each(m_predicateDeclarations.cbegin(), m_predicateDeclarations.cend(),
-		[&](const auto &predicate)
-		{
-			if (!predicate->isDeclared())
-				throw ConsistencyException("Predicate \"" + predicate->name() + "\" used but never declared");
-		});
-
 	// Verify that constants are unique
 	// Verify that all primitive types are unique
 	// Check for case-sensitivity issues
diff --git a/src/plasp/pddl/Problem.cpp b/src/plasp/pddl/Problem.cpp
index 490b4e4..4ec03cc 100644
--- a/src/plasp/pddl/Problem.cpp
+++ b/src/plasp/pddl/Problem.cpp
@@ -159,7 +159,7 @@ void Problem::parseRequirementSection()
 		m_context.parser.skipWhiteSpace();
 	}
 
-	// TODO: Do this check only once the domain is parsed
+	// TODO: do this check only once the domain is parsed
 	// If no requirements are specified, assume STRIPS
 	if (m_requirements.empty())
 		m_requirements.emplace_back(Requirement::Type::STRIPS);
diff --git a/src/plasp/pddl/expressions/Constant.cpp b/src/plasp/pddl/expressions/Constant.cpp
index 3e4c004..12a88e1 100644
--- a/src/plasp/pddl/expressions/Constant.cpp
+++ b/src/plasp/pddl/expressions/Constant.cpp
@@ -45,8 +45,6 @@ ConstantPointer Constant::parseDeclaration(Context &context)
 	// Flag constant for potentially upcoming type declaration
 	constant->setDirty();
 
-	// TODO: Store constant in hash map
-
 	return constant;
 }
 
@@ -141,12 +139,12 @@ Constant *Constant::parseAndFind(Context &context, const ExpressionContext &expr
 
 Constant *Constant::parseAndFind(const std::string &constantName, const Constants &constants)
 {
-	// TODO: use hash map
 	const auto match = std::find_if(constants.cbegin(), constants.cend(),
 		[&](const auto &constant)
 		{
 			return constant->name() == constantName;
 		});
+
 	const auto constantExists = (match != constants.cend());
 
 	if (!constantExists)
diff --git a/src/plasp/pddl/expressions/PrimitiveType.cpp b/src/plasp/pddl/expressions/PrimitiveType.cpp
index 86c8141..fb61e86 100644
--- a/src/plasp/pddl/expressions/PrimitiveType.cpp
+++ b/src/plasp/pddl/expressions/PrimitiveType.cpp
@@ -46,7 +46,6 @@ void PrimitiveType::parseDeclaration(Context &context, Domain &domain)
 
 	const auto typeName = context.parser.parseIdentifier(isIdentifier);
 
-	// TODO: use hash map
 	const auto match = std::find_if(types.cbegin(), types.cend(),
 		[&](const auto &primitiveType)
 		{
@@ -113,7 +112,6 @@ PrimitiveType *PrimitiveType::parseAndFind(Context &context, Domain &domain)
 
 	BOOST_ASSERT(!typeName.empty());
 
-	// TODO: use hash map
 	const auto match = std::find_if(types.cbegin(), types.cend(),
 		[&](const auto &primitiveType)
 		{
diff --git a/tests/TestUtils.cpp b/tests/TestUtils.cpp
index 192bef2..89b3a48 100644
--- a/tests/TestUtils.cpp
+++ b/tests/TestUtils.cpp
@@ -21,6 +21,7 @@ TEST(UtilsTests, ParseSimple)
 	ASSERT_THROW(p.expect<std::string>("expected"), plasp::utils::ParserException);
 
 	// TODO: test case-insensitive input
+	// TODO: test probing
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////