diff --git a/src/bignum.h b/src/bignum.h
index 4ba0795202eae2e031e5826a0514a31771053bfb..818daaaf961ab98d4ebe6becdcdff3a6d8a3b8dc 100644
--- a/src/bignum.h
+++ b/src/bignum.h
@@ -4,12 +4,12 @@
 || for more information.
 */
 
-#include "global.h"
-#include "pike_int_types.h"
-
 #ifndef BIGNUM_H
 #define BIGNUM_H
 
+#include "global.h"
+#include "pike_int_types.h"
+
 /* Note: These functions assume some properties of the CPU. */
 
 #define INT_TYPE_SIGN(x)             ((x) < 0)
diff --git a/src/module_support.h b/src/module_support.h
index 4c0145fdef9418ccb3eb50c1bb5d37fe0996cdd6..ba389e2cf1c0f4cce4c8826d40d11c3aca3eed1d 100644
--- a/src/module_support.h
+++ b/src/module_support.h
@@ -5,6 +5,7 @@
 */
 
 #ifndef MODULE_SUPPORT_H
+#define MODULE_SUPPORT_H
 
 #include "module.h"
 
diff --git a/src/pike_security.h b/src/pike_security.h
index b53ce65f14a7cdd3953368f28482621dfe88abae..557773d160e9276f1992cf6a1028e1ed77974312 100644
--- a/src/pike_security.h
+++ b/src/pike_security.h
@@ -4,11 +4,11 @@
 || for more information.
 */
 
-#include "global.h"
-
 #ifndef SECURITY_H
 #define SECURITY_H
 
+#include "global.h"
+
 #ifdef PIKE_SECURITY
 #include "object.h"