diff --git a/include/eigenpy/deprecation-policy.hpp b/include/eigenpy/deprecation-policy.hpp
index 061cd8012b49563b8b347c49eb0fe4f1d88575ef..85dc0096804bbbac609c4cd8085d7e7468846a37 100644
--- a/include/eigenpy/deprecation-policy.hpp
+++ b/include/eigenpy/deprecation-policy.hpp
@@ -19,6 +19,8 @@ constexpr PyObject *deprecationTypeToPyObj(DeprecationType dep) {
       return PyExc_DeprecationWarning;
     case DeprecationType::FUTURE:
       return PyExc_FutureWarning;
+    default:  // The switch handles all cases explicitly, this should never be triggered.
+      throw std::invalid_argument("Undefined DeprecationType - this should never be triggered.");
   }
 }