diff --git a/mc/mc.h b/mc/mc.h
index 879c298c..25444dad 100644
--- a/mc/mc.h
+++ b/mc/mc.h
@@ -18,6 +18,9 @@
  * media center
  */
 
+#ifndef MC_H
+#define MC_H
+
 /* include other h files */
 #include "arch.h"
 #include "parse.h"
@@ -102,3 +105,5 @@ struct mod
     int height;
     int bpp;
 };
+
+#endif // MC_H
diff --git a/neutrinordp/xrdp-neutrinordp.h b/neutrinordp/xrdp-neutrinordp.h
index 55601c08..9cce063c 100644
--- a/neutrinordp/xrdp-neutrinordp.h
+++ b/neutrinordp/xrdp-neutrinordp.h
@@ -17,6 +17,9 @@
  * limitations under the License.
  */
 
+#ifndef XRDP_NEUTRINORDP_H
+#define XRDP_NEUTRINORDP_H
+
 /* include other h files */
 #include "arch.h"
 #include "parse.h"
@@ -235,3 +238,5 @@ struct mod
     int allow_client_kbd_settings;
     struct kbd_overrides kbd_overrides; /* neutrinordp.overide_kbd_* values */
 };
+
+#endif // XRDP_NEUTRINORDP_H
diff --git a/sesman/chansrv/fifo.h b/sesman/chansrv/fifo.h
index dd5f696e..2dbec364 100644
--- a/sesman/chansrv/fifo.h
+++ b/sesman/chansrv/fifo.h
@@ -16,6 +16,9 @@
  * limitations under the License.
  */
 
+#ifndef FIFO_H
+#define FIFO_H
+
 /* FIFO implementation to store a pointer to a user struct */
 
 typedef struct fifo
@@ -33,3 +36,4 @@ int   fifo_insert(FIFO *fp, void *data);
 void *fifo_remove(FIFO *fp);
 void *fifo_peek(FIFO *fp);
 
+#endif // FIFO_H
diff --git a/xup/xup.h b/xup/xup.h
index 4f4b415b..f8c64221 100644
--- a/xup/xup.h
+++ b/xup/xup.h
@@ -18,6 +18,9 @@
  * libxup main header file
  */
 
+#ifndef XUP_H
+#define XUP_H
+
 /* include other h files */
 #include "arch.h"
 #include "parse.h"
@@ -176,3 +179,5 @@ struct mod
     char *screen_shmem_pixels;
     struct trans *trans;
 };
+
+#endif // XUP_H