diff --git a/cpmpy/transformations/flatten_model.py b/cpmpy/transformations/flatten_model.py
index 401e7f2d5..bb9d0a82e 100644
--- a/cpmpy/transformations/flatten_model.py
+++ b/cpmpy/transformations/flatten_model.py
@@ -245,7 +245,12 @@ def flatten_constraint(expr):
             # Reification (double implication): Boolexpr == Var
             # normalize the lhs (does not have to be a var, hence we call normalize instead of get_or_make_var
             if exprname == '==' and lexpr.is_bool():
-                (lhs, lcons) = normalized_boolexpr(lexpr)
+                if rvar.is_bool():
+                    # this is a reification
+                    (lhs, lcons) = normalized_boolexpr(lexpr)
+                else:
+                    # integer comparison
+                    (lhs, lcons) = get_or_make_var(lexpr)
             else:
                 (lhs, lcons) = normalized_numexpr(lexpr)