diff --git a/h/arch.h b/h/arch.h
index 78a0bc3b..e5518d9b 100644
--- a/h/arch.h
+++ b/h/arch.h
@@ -3,6 +3,10 @@
  * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
  * See the copyright notice in the ACK home directory, in the file "Copyright".
  */
+
+#ifndef __ARCH_H_INCLUDED
+#define __ARCH_H_INCLUDED
+
 #define	ARMAG	0177545
 #define AALMAG	0177454
 
@@ -17,3 +21,5 @@ struct	ar_hdr {
 
 #define AR_TOTAL	26
 #define AR_SIZE		22
+
+#endif /* __ARCH_H_INCLUDED */
diff --git a/h/cg_pattern.h b/h/cg_pattern.h
index 46dac7c2..f7a81773 100644
--- a/h/cg_pattern.h
+++ b/h/cg_pattern.h
@@ -98,7 +98,7 @@ typedef struct {        /* splitting coercions */
 	int c2_repl[MAXSPLIT];  /* replacement instances */
 	int c2_codep;           /* code index */
 } c2_t,*c2_p;
-#endif MAXSPLIT
+#endif /* MAXSPLIT */
 
 typedef struct {        /* one to one coercions */
 	int c3_texpno;          /* token expression number */
diff --git a/h/cgg_cg.h b/h/cgg_cg.h
index 7593f5d6..b4b4cd75 100644
--- a/h/cgg_cg.h
+++ b/h/cgg_cg.h
@@ -150,7 +150,7 @@ typedef struct {        /* splitting coercions */
 	short c2_repl[MAXSPLIT];/* replacement instances */
 	short c2_codep;         /* code index */
 } c2_t,*c2_p;
-#endif MAXSPLIT
+#endif /* MAXSPLIT */
 
 typedef struct {        /* one to one coercions */
 	short c3_texpno;        /* token expression number */
diff --git a/h/m2_traps.h b/h/m2_traps.h
index e0639292..9ea6330f 100644
--- a/h/m2_traps.h
+++ b/h/m2_traps.h
@@ -1,3 +1,9 @@
+/* $Header$ */
+/*
+ * (c) copyright 1990 by the Vrije Universiteit, Amsterdam, The Netherlands.
+ * See the copyright notice in the ACK home directory, in the file "Copyright".
+ */
+
 /* Modula-2 runtime errors */
 
 #define M2_TOOLARGE	64	/* stack of process too large */
diff --git a/h/out.h b/h/out.h
index 67048230..0834f665 100644
--- a/h/out.h
+++ b/h/out.h
@@ -3,12 +3,15 @@
  * See the copyright notice in the ACK home directory, in the file "Copyright".
  */
 /* $Header$ */
+
+#ifndef __OUT_H_INCLUDED
+#define __OUT_H_INCLUDED
 /*
  * output format for ACK assemblers
  */
 #ifndef ushort
 #define ushort	unsigned short
-#endif ushort
+#endif /* ushort */
 
 struct outhead {
 	ushort 	oh_magic;	/* magic number */
@@ -119,3 +122,5 @@ struct outname {
 #define OFF_RELO(x)	(OFF_EMIT(x) + (x).oh_nemit)
 #define OFF_NAME(x)	(OFF_RELO(x) + ((long)(x).oh_nrelo * SZ_RELO))
 #define OFF_CHAR(x)	(OFF_NAME(x) + ((long)(x).oh_nname * SZ_NAME))
+
+#endif /* __OUT_H_INCLUDED */
diff --git a/h/ranlib.h b/h/ranlib.h
index 56eba14c..84f4d6c9 100644
--- a/h/ranlib.h
+++ b/h/ranlib.h
@@ -4,9 +4,12 @@
  */
 /* $Header$ */
 
+#ifndef __RANLIB_H_INCLUDED
+#define __RANLIB_H_INCLUDED
+
 #ifndef SYMDEF
 #	define SYMDEF	"__.SYMDEF"
-#endif SYMDEF
+#endif /* SYMDEF */
 
 /*
  * Structure of the SYMDEF table of contents for an archive.
@@ -27,3 +30,5 @@ struct ranlib {
 
 #define SZ_RAN	8
 #define SF_RAN	"44"
+
+#endif /* __RANLIB_H_INCLUDED */
diff --git a/h/stb.h b/h/stb.h
index 07464761..c36be939 100644
--- a/h/stb.h
+++ b/h/stb.h
@@ -1,4 +1,8 @@
 /* $Header$ */
+/*
+ * (c) copyright 1990 by the Vrije Universiteit, Amsterdam, The Netherlands.
+ * See the copyright notice in the ACK home directory, in the file "Copyright".
+ */
 
 /* debugger symbol table types, as in DBX */