1 files changed, 2 insertions, 2 deletions
diff --git a/expression_base.cpp b/expression_base.cpp
index 3202328..2457571 100644
--- a/expression_base.cpp
+++ b/expression_base.cpp
@@ -11,11 +11,11 @@ using std::string;
 Expression::Expression(Expression *left, Expression *right, token_type type)
   : left(left), right(right), type(type) {}
 
-const Expression *Expression::getLeft() {
+const Expression *Expression::getLeft() const {
   return left;
 }
 
-const Expression *Expression::getRight() {
+const Expression *Expression::getRight() const {
   return right;
 }