diff --git a/src/ast/substitution/substitution.cpp b/src/ast/substitution/substitution.cpp
index 7e981aab8..e16fdf3dd 100644
--- a/src/ast/substitution/substitution.cpp
+++ b/src/ast/substitution/substitution.cpp
@@ -112,7 +112,7 @@ void substitution::apply(unsigned num_actual_offsets, unsigned const * deltas, e
                 TRACE("subst_bug", tout << "visited: " << visited << ", n1: " << mk_pp(n1.get_expr(), m_manager) << " : " << n1.get_offset() << "\n";);
                 if (visited) {
                     m_todo.pop_back();
-                    expr * new_expr;
+                    expr * new_expr = nullptr;
                     m_apply_cache.find(n1, new_expr);
                     m_apply_cache.insert(n, new_expr);
                     TRACE("subst_bug", tout << "1. insert n: " << mk_pp(n.get_expr(), m_manager) << " : " << n.get_offset() 
diff --git a/src/util/array.h b/src/util/array.h
index 9f0321777..41b36693a 100644
--- a/src/util/array.h
+++ b/src/util/array.h
@@ -151,7 +151,7 @@ public:
         if (m_data == nullptr) {
             return 0;  
         }
-        return static_cast<unsigned>(reinterpret_cast<size_t *>(m_data)[SIZE_IDX]); 
+        return static_cast<unsigned>(reinterpret_cast<size_t *>(m_data)[ARRAY_SIZE_IDX]); 
     }
     
     bool empty() const { return m_data == nullptr; }