diff --git a/src/math/lp/lar_solver.cpp b/src/math/lp/lar_solver.cpp
index 1e8a31342..72e88e97f 100644
--- a/src/math/lp/lar_solver.cpp
+++ b/src/math/lp/lar_solver.cpp
@@ -2368,6 +2368,9 @@ std::pair<constraint_index, constraint_index> lar_solver::add_equality(lpvar j,
     coeffs.push_back(std::make_pair(mpq(1),j));
     coeffs.push_back(std::make_pair(mpq(-1),k));    
     unsigned term_index = add_term(coeffs, UINT_MAX); // UINT_MAX is the external null var
+    if (get_column_value(j) != get_column_value(k))
+        set_status(lp_status::UNKNOWN);
+
     return std::pair<constraint_index, constraint_index>(
         add_var_bound(term_index, lconstraint_kind::LE, mpq(0)),
         add_var_bound(term_index, lconstraint_kind::GE, mpq(0)));