diff --git a/src/math/interval/dep_intervals.h b/src/math/interval/dep_intervals.h
index 973cadb4b..c52477a4c 100644
--- a/src/math/interval/dep_intervals.h
+++ b/src/math/interval/dep_intervals.h
@@ -209,8 +209,7 @@ public:
     }
 
     template <enum with_deps_t wd>
-    interval power(const interval& a, unsigned n) {
-        interval b;
+        void power(const interval& a, unsigned n, interval& b) {
         if (with_deps == wd) {
             interval_deps_combine_rule combine_rule;
             m_imanager.power(a, n, b, combine_rule);
@@ -221,7 +220,6 @@ public:
         }
         TRACE("dep_intervals", tout << "power of "; display(tout, a) << " = ";
               display(tout, b) << "\n"; );
-        return b;
     }
 
     template <enum with_deps_t wd>
diff --git a/src/math/lp/nla_intervals.cpp b/src/math/lp/nla_intervals.cpp
index f4abb3ea8..4d131b798 100644
--- a/src/math/lp/nla_intervals.cpp
+++ b/src/math/lp/nla_intervals.cpp
@@ -446,7 +446,8 @@ bool intervals::interval_of_mul(const nex_mul& e, scoped_dep_interval& a, const
 template <e_with_deps wd>
 void intervals::to_power(scoped_dep_interval& a, unsigned p) {
     if (p == 1) return;
-    interval b = m_dep_intervals.power<wd>(a, p);
+    scoped_dep_interval b(m_dep_intervals);
+    m_dep_intervals.power<wd>(a, p, b);
     m_dep_intervals.set<wd>(a, b);
 
 }
diff --git a/src/smt/theory_seq.cpp b/src/smt/theory_seq.cpp
index ce6c512ae..944e5a9aa 100644
--- a/src/smt/theory_seq.cpp
+++ b/src/smt/theory_seq.cpp
@@ -1970,8 +1970,9 @@ bool theory_seq::check_length_coherence() {
 }
 
 bool theory_seq::fixed_length(bool is_zero) {
-    bool found = false;
-    for (auto e : m_length) {
+    bool found = false;    
+    for (unsigned i = 0; i < m_length.size(); ++i) {
+        expr* e = m_length.get(i);
         if (fixed_length(e, is_zero)) {
             found = true;
         }