diff --git a/libsolidity/ast/ASTJsonExporter.cpp b/libsolidity/ast/ASTJsonExporter.cpp
index f2b6ff48e..5e86cc70e 100644
--- a/libsolidity/ast/ASTJsonExporter.cpp
+++ b/libsolidity/ast/ASTJsonExporter.cpp
@@ -344,7 +344,12 @@ bool ASTJsonExporter::visit(UsingForDirective const& _node)
 		attributes.emplace_back("functionList", std::move(functionList));
 	}
 	else
-		attributes.emplace_back("libraryName", toJson(*_node.functionsOrLibrary().front()));
+	{
+		solAssert(_node.functionsAndOperators().size() == 1);
+		auto const& functionAndOperator = _node.functionsAndOperators().front();
+		solAssert(!functionAndOperator.second.has_value());
+		attributes.emplace_back("libraryName", toJson(*(functionAndOperator.first)));
+	}
 	attributes.emplace_back("global", _node.global());
 
 	setJsonNode(_node, "UsingForDirective", std::move(attributes));
diff --git a/test/libsolidity/syntaxTests/operators/custom/operator_with_calldata_parameters.sol b/test/libsolidity/syntaxTests/operators/custom/operator_with_calldata_parameters.sol
index 081291ece..7b33b691b 100644
--- a/test/libsolidity/syntaxTests/operators/custom/operator_with_calldata_parameters.sol
+++ b/test/libsolidity/syntaxTests/operators/custom/operator_with_calldata_parameters.sol
@@ -2,7 +2,7 @@ using {add as +} for S;
 
 struct S {
     uint x;
-} 
+}
 
 function add(S calldata, S calldata) pure returns (S calldata r) {
     assembly {