diff --git a/src/cmdstan/write_datetime.hpp b/src/cmdstan/write_datetime.hpp
index 02887ed023..91dfc3f1a2 100644
--- a/src/cmdstan/write_datetime.hpp
+++ b/src/cmdstan/write_datetime.hpp
@@ -9,22 +9,20 @@
 
 namespace cmdstan {
 
-void write_datetime(stan::callbacks::writer &writer) {
+void write_datetime(stan::callbacks::writer& writer) {
   const std::time_t current_datetime
       = std::chrono::system_clock::to_time_t(std::chrono::system_clock::now());
   std::tm* curr_tm = std::localtime(&current_datetime);
   std::stringstream current_datetime_msg;
-  current_datetime_msg << "start_datetime = " 
-  << std::setfill('0') << (1900+curr_tm->tm_year) << "-"
-  << std::setw(2) << (curr_tm->tm_mon+1) << "-"
-  << std::setw(2) << curr_tm->tm_mday << " "
-  << std::setw(2) << curr_tm->tm_hour << ":"
-  << std::setw(2) << curr_tm->tm_min << ":"
-  << std::setw(2) << curr_tm->tm_sec;
+  current_datetime_msg << "start_datetime = " << std::setfill('0')
+                       << (1900 + curr_tm->tm_year) << "-" << std::setw(2)
+                       << (curr_tm->tm_mon + 1) << "-" << std::setw(2)
+                       << curr_tm->tm_mday << " " << std::setw(2)
+                       << curr_tm->tm_hour << ":" << std::setw(2)
+                       << curr_tm->tm_min << ":" << std::setw(2)
+                       << curr_tm->tm_sec;
   writer(current_datetime_msg.str());
 }
 
-
-
 }  // namespace cmdstan
 #endif