Move header #include
diff --git a/src/cpp/server/server_context.cc b/src/cpp/server/server_context.cc
index 71e3b46..92775c9 100644
--- a/src/cpp/server/server_context.cc
+++ b/src/cpp/server/server_context.cc
@@ -32,6 +32,9 @@
  */
 
 #include <grpc++/server_context.h>
+
+#include <mutex>
+
 #include <grpc++/impl/call.h>
 #include <grpc/grpc.h>
 #include <grpc/support/log.h>