diff --git a/python/gtsam/preamble/hybrid.h b/python/gtsam/preamble/hybrid.h
index 661215e59..90a062d66 100644
--- a/python/gtsam/preamble/hybrid.h
+++ b/python/gtsam/preamble/hybrid.h
@@ -11,3 +11,10 @@
  * mutations on Python side will not be reflected on C++.
  */
 #include <pybind11/stl.h>
+
+// NOTE: Needed since we are including pybind11/stl.h.
+#ifdef GTSAM_ALLOCATOR_TBB
+PYBIND11_MAKE_OPAQUE(std::vector<gtsam::Key, tbb::tbb_allocator<gtsam::Key>>);
+#else
+PYBIND11_MAKE_OPAQUE(std::vector<gtsam::Key>);
+#endif
diff --git a/python/gtsam/specializations/hybrid.h b/python/gtsam/specializations/hybrid.h
index 8b1378917..e69de29bb 100644
--- a/python/gtsam/specializations/hybrid.h
+++ b/python/gtsam/specializations/hybrid.h
@@ -1 +0,0 @@
-