diff --git a/src/ast/literal.h b/src/ast/literal.h
index 9f91478a2c..783a0f748a 100644
--- a/src/ast/literal.h
+++ b/src/ast/literal.h
@@ -61,7 +61,7 @@ class Literal {
 
  protected:
   /// Constructor
-  Literal(ast::type::Type* type);
+  explicit Literal(ast::type::Type* type);
 
  private:
   ast::type::Type* type_ = nullptr;