diff --git a/libsolidity/analysis/PostTypeChecker.cpp b/libsolidity/analysis/PostTypeChecker.cpp
index a18ee4320..6ed306269 100644
--- a/libsolidity/analysis/PostTypeChecker.cpp
+++ b/libsolidity/analysis/PostTypeChecker.cpp
@@ -82,6 +82,16 @@ bool PostTypeChecker::visit(Identifier const& _identifier)
 	return callVisit(_identifier);
 }
 
+bool PostTypeChecker::visit(StructDefinition const& _struct)
+{
+	return callVisit(_struct);
+}
+
+void PostTypeChecker::endVisit(StructDefinition const& _struct)
+{
+	callEndVisit(_struct);
+}
+
 bool PostTypeChecker::visit(ModifierInvocation const& _modifierInvocation)
 {
 	return callVisit(_modifierInvocation);
@@ -282,6 +292,55 @@ private:
 	bool m_insideEmitStatement = false;
 };
 
+struct NoVariablesInInterfaceChecker: public PostTypeChecker::Checker
+{
+	NoVariablesInInterfaceChecker(ErrorReporter& _errorReporter):
+		Checker(_errorReporter)
+	{}
+
+	bool visit(VariableDeclaration const& _variable) override
+	{
+		// Forbid any variable declarations inside interfaces unless they are part of
+		// * a function's input/output parameters,
+		// * or inside of a struct definition.
+		if (
+			m_scope && m_scope->isInterface()
+			&& !_variable.isCallableOrCatchParameter()
+			&& !m_insideStruct
+		)
+			m_errorReporter.typeError(_variable.location(), "Variables cannot be declared in interfaces.");
+
+		return true;
+	}
+
+	bool visit(ContractDefinition const& _contract) override
+	{
+		m_scope = &_contract;
+		return true;
+	}
+
+	void endVisit(ContractDefinition const&) override
+	{
+		m_scope = nullptr;
+	}
+
+	bool visit(StructDefinition const&) override
+	{
+		solAssert(m_insideStruct >= 0, "");
+		m_insideStruct++;
+		return true;
+	}
+
+	void endVisit(StructDefinition const&) override
+	{
+		m_insideStruct--;
+		solAssert(m_insideStruct >= 0, "");
+	}
+private:
+	ContractDefinition const* m_scope = nullptr;
+	/// Flag indicating whether we are currently inside a StructDefinition.
+	int m_insideStruct = 0;
+};
 }
 
 PostTypeChecker::PostTypeChecker(langutil::ErrorReporter& _errorReporter): m_errorReporter(_errorReporter)
@@ -290,4 +349,5 @@ PostTypeChecker::PostTypeChecker(langutil::ErrorReporter& _errorReporter): m_err
 	m_checkers.push_back(make_shared<OverrideSpecifierChecker>(_errorReporter));
 	m_checkers.push_back(make_shared<ModifierContextChecker>(_errorReporter));
 	m_checkers.push_back(make_shared<EventOutsideEmitChecker>(_errorReporter));
+	m_checkers.push_back(make_shared<NoVariablesInInterfaceChecker>(_errorReporter));
 }
diff --git a/libsolidity/analysis/PostTypeChecker.h b/libsolidity/analysis/PostTypeChecker.h
index 7a48dfb22..0a3358553 100644
--- a/libsolidity/analysis/PostTypeChecker.h
+++ b/libsolidity/analysis/PostTypeChecker.h
@@ -38,6 +38,7 @@ namespace solidity::frontend
  *  - whether override specifiers are actually contracts
  *  - whether a modifier is in a function header
  *  - whether an event is used outside of an emit statement
+ *  - whether a variable is declared in a interface
  *
  *  When adding a new checker, make sure a visitor that forwards calls that your
  *  checker uses exists in PostTypeChecker. Add missing ones.
@@ -76,6 +77,9 @@ private:
 
 	bool visit(Identifier const& _identifier) override;
 
+	bool visit(StructDefinition const& _struct) override;
+	void endVisit(StructDefinition const& _struct) override;
+
 	bool visit(ModifierInvocation const& _modifierInvocation) override;
 	void endVisit(ModifierInvocation const& _modifierInvocation) override;
 
diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index 6315ac15f..eb1b6ddcc 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -317,10 +317,7 @@ bool TypeChecker::visit(StructDefinition const& _struct)
 	if (CycleDetector<StructDefinition>(visitor).run(_struct) != nullptr)
 		m_errorReporter.fatalTypeError(_struct.location(), "Recursive struct definition.");
 
-	bool insideStruct = true;
-	swap(insideStruct, m_insideStruct);
 	ASTNode::listAccept(_struct.members(), *this);
-	m_insideStruct = insideStruct;
 
 	return false;
 }
@@ -451,16 +448,6 @@ bool TypeChecker::visit(FunctionDefinition const& _function)
 
 bool TypeChecker::visit(VariableDeclaration const& _variable)
 {
-	// Forbid any variable declarations inside interfaces unless they are part of
-	// * a function's input/output parameters,
-	// * or inside of a struct definition.
-	if (
-		m_scope->isInterface()
-		&& !_variable.isCallableOrCatchParameter()
-		&& !m_insideStruct
-	)
-		m_errorReporter.typeError(_variable.location(), "Variables cannot be declared in interfaces.");
-
 	if (_variable.typeName())
 		_variable.typeName()->accept(*this);
 
diff --git a/libsolidity/analysis/TypeChecker.h b/libsolidity/analysis/TypeChecker.h
index 1e30ac1b5..c7443b29c 100644
--- a/libsolidity/analysis/TypeChecker.h
+++ b/libsolidity/analysis/TypeChecker.h
@@ -163,9 +163,6 @@ private:
 
 	langutil::EVMVersion m_evmVersion;
 
-	/// Flag indicating whether we are currently inside a StructDefinition.
-	bool m_insideStruct = false;
-
 	langutil::ErrorReporter& m_errorReporter;
 };