diff --git a/modules/geom/pymod/export_mat4.cc b/modules/geom/pymod/export_mat4.cc
index b152e1904759d9e5d5bd6b488a77e7e40adb13b2..4e03bcb166ef7e9d2736f13ca5182cb5e3a03523 100644
--- a/modules/geom/pymod/export_mat4.cc
+++ b/modules/geom/pymod/export_mat4.cc
@@ -114,6 +114,7 @@ void export_Mat4()
     .def(init<Real,Real,Real,Real,Real,Real,Real,Real,Real,Real,Real,Real,Real,Real,Real,Real>())
     .def(init<const Mat2&>())
     .def(init<const Mat3&>())
+    .def(init<const Mat4&>())
     .def(self += self)
     .def(self -= self)
     .def(self + self)