diff --git a/pystencils/data_types.py b/pystencils/data_types.py
index 28fc4b32c4084ed319c4788b2e0b4ade0d0ccb7d..4fc236e539fa6e6a0ab2ef0686d22bcd38a119bb 100644
--- a/pystencils/data_types.py
+++ b/pystencils/data_types.py
@@ -242,6 +242,9 @@ class TypedSymbol(sp.Symbol):
     def __getnewargs__(self):
         return self.name, self.dtype
 
+    def __getnewargs_ex__(self):
+        return ((self.name, self.dtype), self.assumptions0)
+
     @property
     def canonical(self):
         return self