diff --git a/porthole/include/porthole/client.h b/porthole/include/porthole/client.h
index ec88a46c..76de6a94 100644
--- a/porthole/include/porthole/client.h
+++ b/porthole/include/porthole/client.h
@@ -17,6 +17,8 @@ this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 Place, Suite 330, Boston, MA 02111-1307 USA
 */
 
+#pragma once
+
 #include "types.h"
 
 typedef struct PortholeClient *PortholeClient;
diff --git a/porthole/include/porthole/device.h b/porthole/include/porthole/device.h
index df1af02d..b4979907 100644
--- a/porthole/include/porthole/device.h
+++ b/porthole/include/porthole/device.h
@@ -17,6 +17,8 @@ this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 Place, Suite 330, Boston, MA 02111-1307 USA
 */
 
+#pragma once
+
 #include <stdbool.h>
 #include <stdint.h>
 
diff --git a/porthole/include/porthole/types.h b/porthole/include/porthole/types.h
index 0abca45a..03d9ad94 100644
--- a/porthole/include/porthole/types.h
+++ b/porthole/include/porthole/types.h
@@ -17,6 +17,8 @@ this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 Place, Suite 330, Boston, MA 02111-1307 USA
 */
 
+#pragma once
+
 #include <stdbool.h>
 #include <stdint.h>
 
diff --git a/porthole/include/porthole/util.h b/porthole/include/porthole/util.h
index f5816b38..d8b4a4b3 100644
--- a/porthole/include/porthole/util.h
+++ b/porthole/include/porthole/util.h
@@ -17,6 +17,8 @@ this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 Place, Suite 330, Boston, MA 02111-1307 USA
 */
 
+#pragma once
+
 #include "types.h"
 #include <sys/types.h>