diff --git a/src/api/c++/z3++.h b/src/api/c++/z3++.h
index 175fe87fc..edbc11e7d 100644
--- a/src/api/c++/z3++.h
+++ b/src/api/c++/z3++.h
@@ -1799,13 +1799,13 @@ namespace z3 {
             unsigned m_index;
         public:
             iterator(ast_vector_tpl const* v, unsigned i): m_vector(v), m_index(i) {}
-            iterator(iterator& other): m_vector(other.m_vector), m_index(other.m_index) {}
+            iterator(iterator const& other): m_vector(other.m_vector), m_index(other.m_index) {}
             iterator operator=(iterator const& other) { m_vector = other.m_vector; m_index = other.m_index; return *this; }
 
-            bool operator==(iterator const& other) {
+            bool operator==(iterator const& other) const {
                 return other.m_index == m_index;
             };
-            bool operator!=(iterator const& other) {
+            bool operator!=(iterator const& other) const {
                 return other.m_index != m_index;
             };
             iterator& operator++() {