diff --git a/src/mfast/ext_ref.h b/src/mfast/ext_ref.h
index c9a569fa..c7a41800 100644
--- a/src/mfast/ext_ref.h
+++ b/src/mfast/ext_ref.h
@@ -128,7 +128,7 @@ class ext_cref<decimal_cref, std::tuple<ExponentOp, MantissaOp>, Properties> {
   exponent_type get_exponent() const {
     return exponent_type(base_.get_exponent());
   }
-  bool present() const { return !this->optional() || base_.present(); }
+  bool present() const { return !base_.optional() || base_.present(); }
 
 private:
   decimal_cref base_;