diff --git a/aos/common/queue.cc b/aos/common/queue.cc
index 7e7f2a1..b3a4799 100644
--- a/aos/common/queue.cc
+++ b/aos/common/queue.cc
@@ -30,7 +30,7 @@
 }
 
 size_t Message::Print(char *buffer, int length) const {
-  return snprintf(buffer, length, "%"PRId32".%09"PRId32"s",
+  return snprintf(buffer, length, "%" PRId32 ".%09" PRId32 "s",
                   sent_time.sec(), sent_time.nsec());
 }