diff --git a/src/leaf_data_type.hpp b/src/leaf_data_type.hpp
index c3c30c9..f1619ec 100644
--- a/src/leaf_data_type.hpp
+++ b/src/leaf_data_type.hpp
@@ -71,6 +71,10 @@
     std::set<std::string> m_allowedValues;
 };
 struct LeafRef;
+struct InstanceIdentifier {
+    InstanceIdentifier();
+    bool operator==(const InstanceIdentifier& other) const;
+};
 struct Union;
 using LeafDataType = std::variant<
     yang::String,
@@ -90,6 +94,7 @@
     yang::IdentityRef,
     yang::Bits,
     yang::LeafRef,
+    yang::InstanceIdentifier,
     yang::Union
 >;
 struct TypeInfo;