diff --git a/src/network/networktransport-impl.h b/src/network/networktransport-impl.h
index 4073982..f3e74e8 100644
--- a/src/network/networktransport-impl.h
+++ b/src/network/networktransport-impl.h
@@ -30,6 +30,9 @@
     also delete it here.
 */
 
+#ifndef NETWORK_TRANSPORT_IMPL_HPP
+#define NETWORK_TRANSPORT_IMPL_HPP
+
 #include "networktransport.h"
 
 #include "transportsender-impl.h"
@@ -200,3 +203,5 @@ string Transport<MyState, RemoteState>::get_remote_diff( void )
 
   return ret;
 }
+
+#endif
diff --git a/src/network/transportsender-impl.h b/src/network/transportsender-impl.h
index 7e4d58c..9d5b54d 100644
--- a/src/network/transportsender-impl.h
+++ b/src/network/transportsender-impl.h
@@ -30,6 +30,9 @@
     also delete it here.
 */
 
+#ifndef TRANSPORT_SENDER_IMPL_HPP
+#define TRANSPORT_SENDER_IMPL_HPP
+
 #include <algorithm>
 #include <list>
 #include <stdio.h>
@@ -405,3 +408,5 @@ void TransportSender<MyState>::attempt_prospective_resend_optimization( string &
     proposed_diff = resend_diff;
   }
 }
+
+#endif