diff --git a/include/matador/sql/basic_condition.hpp b/include/matador/sql/basic_condition.hpp
index 0f9a135..daa250f 100644
--- a/include/matador/sql/basic_condition.hpp
+++ b/include/matador/sql/basic_condition.hpp
@@ -33,7 +33,7 @@ public:
     LIKE
   };
 
-  virtual std::string evaluate(dialect &dialect, query_context &query) const = 0;
+  virtual std::string evaluate(const dialect &dialect, query_context &query) const = 0;
 
   static std::unordered_map<operand_t, std::string> operands;
 };
diff --git a/include/matador/sql/condition.hpp b/include/matador/sql/condition.hpp
index a85f5d7..e390c3f 100644
--- a/include/matador/sql/condition.hpp
+++ b/include/matador/sql/condition.hpp
@@ -37,7 +37,7 @@ public:
 
     placeholder value;
 
-    std::string evaluate(dialect &d, query_context &query) const override;
+    std::string evaluate(const dialect &d, query_context &query) const override;
 };
 
 template<class T>
@@ -54,7 +54,7 @@ public:
 
   T value;
 
-  std::string evaluate(dialect &d, query_context &query) const override
+  std::string evaluate(const dialect &d, query_context &query) const override
   {
     query.bind_vars.emplace_back(field_.name);
     return d.prepare_identifier(field_) + " " + operand + " " + std::to_string(value);
@@ -74,7 +74,7 @@ public:
 
   T value;
 
-  std::string evaluate(dialect &d, query_context &query) const override
+  std::string evaluate(const dialect &d, query_context &query) const override
   {
     query.bind_vars.emplace_back(field_.name);
     return d.prepare_identifier(field_) + " " + operand + " '" + value + "'";
@@ -95,7 +95,7 @@ public:
 
   T value;
 
-  std::string evaluate(dialect &d, query_context &query) const override
+  std::string evaluate(const dialect &d, query_context &query) const override
   {
     return std::to_string(value) + " " + operand + " " + d.prepare_identifier(field_);
   }
@@ -114,7 +114,7 @@ public:
 
   T value;
 
-  std::string evaluate(dialect &d, query_context &query) const override
+  std::string evaluate(const dialect &d, query_context &query) const override
   {
     return "'" + std::to_string(value) + "' " + operand + " " + d.prepare_identifier(field_);
   }
@@ -156,7 +156,7 @@ public:
    * @param d The d used to evaluate
    * @return A condition IN part of the query
    */
-  std::string evaluate(dialect &d, query_context &query) const override {
+  std::string evaluate(const dialect &d, query_context &query) const override {
     auto count = size();
     for (size_t i = 0; i < count; ++i) {
       query.bind_vars.emplace_back(field_.name);
@@ -226,7 +226,7 @@ public:
    * @param d The d used to evaluate
    * @return A condition IN part of the query
    */
-  std::string evaluate(dialect &d, query_context &query) const override;
+  std::string evaluate(const dialect &d, query_context &query) const override;
 
 private:
   query_context &query_;
@@ -261,7 +261,7 @@ public:
    * @param d The d used to evaluate
    * @return A condition BETWEEN part of the query
    */
-  std::string evaluate(dialect &d, query_context &query) const override {
+  std::string evaluate(const dialect &d, query_context &query) const override {
     query.bind_vars.emplace_back(field_.name);
     query.bind_vars.emplace_back(field_.name);
     return d.prepare_identifier(field_) + " BETWEEN " + std::to_string(range_.first) + " AND " + std::to_string(range_.second);
@@ -303,7 +303,7 @@ public:
    * @param d The d used to evaluate
    * @return The evaluated string based on the compile type
    */
-  std::string evaluate(dialect &d, query_context &query) const override
+  std::string evaluate(const dialect &d, query_context &query) const override
   {
     // ensure the numbering order for host vars
     auto cl = left.evaluate(d, query);
@@ -346,7 +346,7 @@ public:
    * @param d The d used to evaluate
    * @return The evaluated string based on the compile type
    */
-  std::string evaluate(dialect &d, query_context &query) const override
+  std::string evaluate(const dialect &d, query_context &query) const override
   {
     return operand + " (" + cond.evaluate(d) + ")";
   }
@@ -369,7 +369,7 @@ public:
    * @param d The d used to evaluate
    * @return The evaluated string based on the compile type
    */
-  std::string evaluate(dialect &d, query_context &query) const override
+  std::string evaluate(const dialect &d, query_context &query) const override
   {
     return d.prepare_identifier(field_) + " " + operand + " " + d.prepare_identifier(other_column_);
   }