diff --git a/src/static_schema.cpp b/src/static_schema.cpp
index 511e420..0eb564a 100644
--- a/src/static_schema.cpp
+++ b/src/static_schema.cpp
@@ -300,3 +300,8 @@
 {
     throw std::runtime_error{"Internal error: StaticSchema::leafrefPath(std::string) not implemented. The tests should not have called this overload."};
 }
+
+bool StaticSchema::leafIsKey([[maybe_unused]] const std::string& leafPath) const
+{
+    throw std::runtime_error{"Internal error: StaticSchema::leafIsKey(std::string) not implemented. The tests should not have called this overload."};
+}