diff --git a/src/allreduce_base.cc b/src/allreduce_base.cc
index d5cd068ea..d3b7502ff 100644
--- a/src/allreduce_base.cc
+++ b/src/allreduce_base.cc
@@ -199,7 +199,7 @@ utils::TCPSocket AllreduceBase::ConnectTracker(void) const {
         fprintf(stderr, "connect to (failed): [%s]\n", tracker_uri.c_str());
         utils::Socket::Error("Connect");
       } else {
-        fprintf(stderr, "retry connect to ip(retry time %d): [%s]\n", retry, tracker_uri.c_str());      
+        fprintf(stderr, "retry connect to ip(retry time %d): [%s]\n", retry, tracker_uri.c_str());
         #ifdef _MSC_VER
         Sleep(1);
         #else