diff --git a/src/math/lp/dioph_eq.cpp b/src/math/lp/dioph_eq.cpp
index c6719e0e38..ba38d2227f 100644
--- a/src/math/lp/dioph_eq.cpp
+++ b/src/math/lp/dioph_eq.cpp
@@ -649,16 +649,12 @@ namespace lp {
         struct undo_fixed_column : public trail {
             imp& m_imp;
             unsigned m_j;  // the column that has been added
-            mpq m_fixed_val;  // not const: needs to be reset in undo() to free heap memory
-            undo_fixed_column(imp& s, unsigned j) : m_imp(s), m_j(j), m_fixed_val(s.lra.get_lower_bound(j).x) {
+            undo_fixed_column(imp& s, unsigned j) : m_imp(s), m_j(j) {
                 SASSERT(s.lra.column_is_fixed(j));
             }
 
             void undo() override {
                 m_imp.add_changed_column(m_j);
-                // Free heap-allocated memory in m_fixed_val since this struct is region-allocated
-                // and its destructor won't be called
-                m_fixed_val.reset();
             }
         };