diff --git a/src/sync/sync.h b/src/sync/sync.h
index 0619c3ea3..c69755b14 100644
--- a/src/sync/sync.h
+++ b/src/sync/sync.h
@@ -7,9 +7,10 @@
  */
 #include <cstdio>
 #include <cstring>
+#include <string>
+
 #include "../utils/utils.h"
 #include "../utils/io.h"
-#include <string>
 
 namespace MPI {
 // forward delcaration of MPI::Datatype, but not include content
diff --git a/test/Makefile b/test/Makefile
index 6d135e317..6c943e155 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -11,7 +11,7 @@ else
 endif
 
 # specify tensor path
-BIN = test_group_data test_quantile
+BIN = test_group_data test_quantile test_sock
 
 .PHONY: clean all
 
@@ -19,6 +19,7 @@ all: $(BIN) $(MPIBIN)
 
 test_group_data: test_group_data.cpp ../src/utils/*.h
 test_quantile: test_quantile.cpp ../src/utils/*.h
+test_sock: test_sock.cpp ../src/utils/*.h
 
 $(BIN) : 
 	$(CXX) $(CFLAGS) $(LDFLAGS) -o $@ $(filter %.cpp %.o %.c, $^)