diff --git a/modules/src/malloc/check.h b/modules/src/malloc/check.h
index b2880e742..cae5166cf 100644
--- a/modules/src/malloc/check.h
+++ b/modules/src/malloc/check.h
@@ -8,7 +8,7 @@
 public check_mallinks(), calc_checksum(), check_work_empty();
 public started_working_on(), stopped_working_on();
 
-#else	ifndef	CHECK
+#else	/* ifndef	CHECK */
 
 #define	maldump(n)		abort()
 #define	check_mallinks(s)	0
@@ -17,4 +17,4 @@ public started_working_on(), stopped_working_on();
 #define	stopped_working_on(ml)	0
 #define	check_work_empty(s)	0
 
-#endif	CHECK
+#endif	/* CHECK */
diff --git a/modules/src/malloc/impl.h b/modules/src/malloc/impl.h
index b0d96ef6c..1875bdcf2 100644
--- a/modules/src/malloc/impl.h
+++ b/modules/src/malloc/impl.h
@@ -39,9 +39,9 @@ typedef union _inf mallink;
 */
 #ifndef	NON_STANDARD
 #define	OFF_SET	0
-#else	def NON_STANDARD
+#else	/* def NON_STANDARD */
 #define	OFF_SET	2
-#endif	NON_STANDARD
+#endif	/* NON_STANDARD */
 
 #define	_log_prev_of(ml)	((ml)[-1+OFF_SET]).ptr
 #define	_log_next_of(ml)	((ml)[-2+OFF_SET]).ptr
@@ -54,7 +54,7 @@ typedef union _inf mallink;
 #define	_print_of(ml)		((ml)[-6+OFF_SET]).ui
 #define	_mark_of(ml)		((ml)[-7+OFF_SET]).ui
 #define	N_WORDS			7
-#endif	CHECK
+#endif	/* CHECK */
 
 #define	mallink_size()		(unsigned int) \
 	align((N_WORDS - OFF_SET) * sizeof (mallink))
@@ -65,7 +65,7 @@ typedef union _inf mallink;
 
 #define	set_checksum(ml,e)	(_checksum_of(ml) = (e))
 #define	checksum_of(ml)		(_checksum_of(ml))
-#endif	CHECK
+#endif	/* CHECK */
 
 #define new_mallink(ml)		( _log_prev_of(ml) = 0, \
 				  _log_next_of(ml) = 0, \
@@ -80,14 +80,14 @@ typedef union _inf mallink;
 #ifndef	EXTERN
 #define	private	static
 #define	privatedata	static
-#else	def	EXTERN
+#else	/* def	EXTERN */
 #define	private	extern
 #define	privatedata
-#endif	EXTERN
+#endif	/* EXTERN */
 
 #ifdef	ASSERT
 public m_assert();
 #define	assert(b)		(!(b) ? m_assert(__FILE__, __LINE__) : 0)
-#else	ndef	ASSERT
+#else	/* ndef	ASSERT */
 #define	assert(b)		0
-#endif	ASSERT
+#endif	/* ASSERT */
diff --git a/modules/src/malloc/phys.h b/modules/src/malloc/phys.h
index 82e5e610b..9e4868ec4 100644
--- a/modules/src/malloc/phys.h
+++ b/modules/src/malloc/phys.h
@@ -33,9 +33,9 @@ public Error();
 		(char *)Error("phys_prev_of first_mallink %lx", "somewhere", (long)ml) : \
 		(char *)__phys_prev_of(ml) \
 	)
-#else	ndef	CHECK
+#else	/* ndef	CHECK */
 #define	phys_prev_of(ml)	__phys_prev_of(ml)
-#endif	CHECK
+#endif	/* CHECK */
 
 #define	first_mallink(ml)	(int) (__phys_prev_of(ml) == 0)
 #define	last_mallink(ml)	(int) ((ml) == ml_last)
@@ -69,7 +69,7 @@ public Error();
 #ifdef	CHECK
 #define	set_print(ml,e)		(_print_of(ml) = (e))
 #define	print_of(ml)		(_print_of(ml))
-#endif	CHECK
+#endif	/* CHECK */
 
 public truncate(), combine_chunks();
 public mallink *create_chunk();
diff --git a/modules/src/read_em/em_comp.h b/modules/src/read_em/em_comp.h
index 2c51646dd..2e160b681 100644
--- a/modules/src/read_em/em_comp.h
+++ b/modules/src/read_em/em_comp.h
@@ -72,4 +72,4 @@ extern unsigned int
 	EM_lineno;
 extern int
 	EM_wordsize, EM_pointersize;
-#endif __EMCOMP_INCLUDED__
+#endif /* __EMCOMP_INCLUDED__ */
diff --git a/modules/src/system/system.h b/modules/src/system/system.h
index 72e523e77..af36299dd 100644
--- a/modules/src/system/system.h
+++ b/modules/src/system/system.h
@@ -44,4 +44,4 @@ extern File _sys_ftab[];
 
 /* system's idea of block */
 #define BUFSIZ	1024
-#endif __SYSTEM_INCLUDED__
+#endif /* __SYSTEM_INCLUDED__ */