diff --git a/lib/pddlparse/include/pddlparse/detail/normalization/Reduction.h b/lib/pddlparse/include/pddlparse/detail/normalization/Reduction.h
new file mode 100644
index 0000000..2ee5cc0
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/normalization/Reduction.h
@@ -0,0 +1,26 @@
+#ifndef __PDDL_PARSE__DETAIL__NORMALIZATION__REDUCTION_H
+#define __PDDL_PARSE__DETAIL__NORMALIZATION__REDUCTION_H
+
+#include <pddlparse/ASTForward.h>
+#include <pddlparse/Context.h>
+#include <pddlparse/NormalizedASTForward.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Reduction
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void reduce(ast::Precondition &precondition);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/src/pddlparse/detail/normalization/Precondition.cpp b/lib/pddlparse/src/pddlparse/detail/normalization/Precondition.cpp
index 45977b4..db68191 100644
--- a/lib/pddlparse/src/pddlparse/detail/normalization/Precondition.cpp
+++ b/lib/pddlparse/src/pddlparse/detail/normalization/Precondition.cpp
@@ -5,6 +5,7 @@
 #include <pddlparse/NormalizedAST.h>
 #include <pddlparse/detail/normalization/AtomicFormula.h>
 #include <pddlparse/detail/normalization/CollectFreeVariables.h>
+#include <pddlparse/detail/normalization/Reduction.h>
 
 namespace pddl
 {
@@ -275,6 +276,9 @@ normalizedAST::AndPointer<normalizedAST::Literal> normalize(ast::AndPointer<ast:
 
 normalizedAST::Precondition normalize(ast::Precondition &&precondition, normalizedAST::DerivedPredicateDeclarations &derivedPredicates)
 {
+	// Bring precondition to normal form
+	reduce(precondition);
+
 	return precondition.match(
 		[&](auto &x) -> normalizedAST::Precondition
 		{
diff --git a/lib/pddlparse/src/pddlparse/detail/normalization/Reduction.cpp b/lib/pddlparse/src/pddlparse/detail/normalization/Reduction.cpp
new file mode 100644
index 0000000..9d29cef
--- /dev/null
+++ b/lib/pddlparse/src/pddlparse/detail/normalization/Reduction.cpp
@@ -0,0 +1,95 @@
+#include <pddlparse/detail/normalization/Reduction.h>
+
+#include <pddlparse/AST.h>
+#include <pddlparse/Exception.h>
+#include <pddlparse/NormalizedAST.h>
+#include <pddlparse/detail/normalization/AtomicFormula.h>
+#include <pddlparse/detail/normalization/CollectFreeVariables.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Reduction
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const auto handleUnsupported =
+	[](ast::UnsupportedPointer &unsupported)
+	{
+		throw NormalizationException("“" + unsupported->type + "” expressions in preconditions can’t be normalized currently");
+	};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void eliminateImply(ast::Precondition &precondition)
+{
+	const auto handleAtomicFormula =
+		[](ast::AtomicFormula &)
+		{
+		};
+
+	const auto handleAnd =
+		[](ast::AndPointer<ast::Precondition> &and_)
+		{
+			for (auto &argument : and_->arguments)
+				eliminateImply(argument);
+		};
+
+	const auto handleExists =
+		[](ast::ExistsPointer<ast::Precondition> &exists)
+		{
+			eliminateImply(exists->argument);
+		};
+
+	const auto handleForAll =
+		[](ast::ForAllPointer<ast::Precondition> &forAll)
+		{
+			eliminateImply(forAll->argument);
+		};
+
+	const auto handleImply =
+		[&](ast::ImplyPointer<ast::Precondition> &imply)
+		{
+			eliminateImply(imply->argumentLeft);
+			eliminateImply(imply->argumentRight);
+
+			ast::Or<ast::Precondition>::Arguments arguments;
+			arguments.reserve(2);
+			arguments.emplace_back(std::make_unique<ast::Not<ast::Precondition>>(std::move(imply->argumentLeft)));
+			arguments.emplace_back(std::move(imply->argumentRight));
+
+			precondition = std::make_unique<ast::Or<ast::Precondition>>(std::move(arguments));
+		};
+
+	const auto handleNot =
+		[](ast::NotPointer<ast::Precondition> &not_)
+		{
+			eliminateImply(not_->argument);
+		};
+
+	const auto handleOr =
+		[](ast::OrPointer<ast::Precondition> &or_)
+		{
+			for (auto &argument : or_->arguments)
+				eliminateImply(argument);
+		};
+
+	precondition.match(handleAtomicFormula, handleAnd, handleExists, handleForAll, handleImply, handleNot, handleOr, handleUnsupported);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void reduce(ast::Precondition &precondition)
+{
+	// Replace “imply” statements with disjunctions
+	eliminateImply(precondition);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}