diff --git a/Changelog.md b/Changelog.md
index c70922942..ff183e22b 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -23,6 +23,8 @@ Bugfixes:
  * Commandline Interface: When linking only accept exact matches for library names passed to the ``--libraries`` option. Library names not prefixed with a file name used to match any library with that name.
  * SMTChecker: Fix internal error in magic type access (``block``, ``msg``, ``tx``).
  * TypeChecker: Fix internal error when using user defined value types in public library functions.
+ * TypeChecker: Fix internal error when using arrays and structs with user defined value types before declaration.
+ * TypeChecker: Improved error message for constant variables with (nested) mapping types.
  * Yul Assembler: Fix internal error when function names are not unique.
  * Yul IR Generator: Do not output empty switches/if-bodies for empty contracts.
 
diff --git a/libsolidity/analysis/DeclarationTypeChecker.cpp b/libsolidity/analysis/DeclarationTypeChecker.cpp
index b015939e2..d531fd77f 100644
--- a/libsolidity/analysis/DeclarationTypeChecker.cpp
+++ b/libsolidity/analysis/DeclarationTypeChecker.cpp
@@ -289,7 +289,6 @@ void DeclarationTypeChecker::endVisit(ArrayTypeName const& _typeName)
 		return;
 	}
 
-	solAssert(baseType->storageBytes() != 0, "Illegal base type of storage size zero for array.");
 	if (Expression const* length = _typeName.length())
 	{
 		optional<rational> lengthValue;
diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index f11756b25..0b5f97719 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -1220,6 +1220,14 @@ void TypeChecker::endVisit(RevertStatement const& _revert)
 		m_errorReporter.typeError(1885_error, errorCall.expression().location(), "Expression has to be an error.");
 }
 
+void TypeChecker::endVisit(ArrayTypeName const& _typeName)
+{
+	solAssert(
+		_typeName.baseType().annotation().type &&
+		_typeName.baseType().annotation().type->storageBytes() != 0,
+		"Illegal base type of storage size zero for array."
+	);
+}
 
 bool TypeChecker::visit(VariableDeclarationStatement const& _statement)
 {
diff --git a/libsolidity/analysis/TypeChecker.h b/libsolidity/analysis/TypeChecker.h
index bf5039204..f0820d930 100644
--- a/libsolidity/analysis/TypeChecker.h
+++ b/libsolidity/analysis/TypeChecker.h
@@ -119,6 +119,7 @@ private:
 	void endVisit(InheritanceSpecifier const& _inheritance) override;
 	void endVisit(ModifierDefinition const& _modifier) override;
 	bool visit(FunctionDefinition const& _function) override;
+	void endVisit(ArrayTypeName const& _typeName) override;
 	bool visit(VariableDeclaration const& _variable) override;
 	/// We need to do this manually because we want to pass the bases of the current contract in
 	/// case this is a base constructor call.
diff --git a/test/libsolidity/syntaxTests/userDefinedValueType/forward_reference_array.sol b/test/libsolidity/syntaxTests/userDefinedValueType/forward_reference_array.sol
new file mode 100644
index 000000000..884fb2b5d
--- /dev/null
+++ b/test/libsolidity/syntaxTests/userDefinedValueType/forward_reference_array.sol
@@ -0,0 +1,4 @@
+contract C {
+    Left[] pu1;
+}
+type Left is bytes2;