diff --git a/src/stan/callbacks/multi_writer.hpp b/src/stan/callbacks/multi_writer.hpp
index c54c7ced47..857aa1d8e4 100644
--- a/src/stan/callbacks/multi_writer.hpp
+++ b/src/stan/callbacks/multi_writer.hpp
@@ -35,14 +35,10 @@ class multi_writer {
    */
   template <typename T>
   void operator()(T&& x) {
-    stan::math::for_each([&](auto&& output) {
-      output(x);
-    }, output_);
+    stan::math::for_each([&](auto&& output) { output(x); }, output_);
   }
   void operator()() {
-    stan::math::for_each([](auto&& output) {
-      output();
-    }, output_);
+    stan::math::for_each([](auto&& output) { output(); }, output_);
   }
 
   /**
@@ -50,7 +46,6 @@ class multi_writer {
    */
   inline auto& get_stream() noexcept { return output_; }
 
-
  private:
   /**
    * Output stream