diff --git a/bin/doname.cc b/bin/doname.cc
index 9073de1..165c72c 100644
--- a/bin/doname.cc
+++ b/bin/doname.cc
@@ -43,7 +43,7 @@
 #include <poll.h>
 #include <libintl.h>
 #include <signal.h>
-#if defined(sun) || defined(__sun)
+#ifdef __sun
 // XXX really needed, even on Solaris?
 #include <stropts.h>
 #else
diff --git a/bin/main.cc b/bin/main.cc
index 257e168..3f807aa 100644
--- a/bin/main.cc
+++ b/bin/main.cc
@@ -50,7 +50,7 @@
 #include <fcntl.h>		/* open() */
 #include <ctype.h>
 
-#if defined(sun) || defined(__sun)
+#ifdef __sun
 #	include <sys/systeminfo.h>	/* sysinfo() */
 #else
 #include <sys/sysinfo.h>
@@ -206,7 +206,7 @@ main(int argc, char *argv[])
 
 	struct stat		out_stat, err_stat;
 	hostid = gethostid();
-#if defined(sun) || defined(__sun)
+#ifdef __sun
 	bsd_signals();
 #else
 // XXX necessary on linux?
@@ -488,7 +488,7 @@ main(int argc, char *argv[])
 /*
  *	Enable interrupt handler for alarms
  */
-#if defined(sun) || defined(__sun)
+#ifdef __sun
         (void) bsd_signal(SIGALRM, (SIG_PF)doalarm);
 #else
         (void) bsd_signal(SIGALRM, doalarm);
@@ -926,7 +926,7 @@ read_command_options(register int argc, register char **argv)
 // between Solaris and GNU libc.
 // Also, the '+' is probably a good idea for GNU libc to avoid
 // reording of arguments.
-#if defined(sun) || defined(__sun)
+#ifdef __sun
 #define SUNPRO_CMD_OPTS	"-~Bbc:Ddef:g:ij:K:kM:m:NnO:o:PpqRrSsTtuVvwx:"
 #define SVR4_CMD_OPTS   "-c:ef:g:ij:km:nO:o:pqrsTtVv"
 #else
@@ -1623,7 +1623,7 @@ make_install_prefix(void)
 	char *dir;
 
 	if ((ret = readlink(
-#if defined(sun) || defined(__sun)
+#ifdef __sun
             "/proc/self/path/a.out",
 #else
             "/proc/self/exe",
diff --git a/bin/parallel.cc b/bin/parallel.cc
index a7ffd00..1e25c8b 100644
--- a/bin/parallel.cc
+++ b/bin/parallel.cc
@@ -255,7 +255,7 @@ execute_parallel(Property line, Boolean waitflg, Boolean local)
 #include <sys/ipc.h>		/* ftok() */
 #include <sys/shm.h>		/* shmget(), shmat(), shmdt(), shmctl() */
 #include <semaphore.h>		/* sem_init(), sem_trywait(), sem_post(), sem_destroy() */
-#if defined(sun) || defined(__sun)
+#ifdef __sun
 #include <sys/loadavg.h>	/* getloadavg() */
 #else
 #include <stdlib.h> // getloadavg()
diff --git a/bin/state.cc b/bin/state.cc
index 955fb7d..46f553e 100644
--- a/bin/state.cc
+++ b/bin/state.cc
@@ -39,7 +39,7 @@
 #include <errno.h>		/* errno    */
 #include <locale.h>		/* MB_CUR_MAX    */
 
-#if defined(sun) || defined(__sun)
+#ifdef __sun
 #else
 #include <libintl.h> // gettext()
 #endif
diff --git a/comp/namelen.h b/comp/namelen.h
index b2bee8f..4ab37ad 100644
--- a/comp/namelen.h
+++ b/comp/namelen.h
@@ -2,7 +2,7 @@
 #ifndef COMP_NAMELEN_H
 #define COMP_NAMELEN_H
 
-#if defined(sun) || defined(__sun)
+#ifdef __sun
 #else
 #define MAXNAMELEN 1024
 #endif
diff --git a/comp/timestruc_t.h b/comp/timestruc_t.h
index 6e1c7e1..ca04c84 100644
--- a/comp/timestruc_t.h
+++ b/comp/timestruc_t.h
@@ -2,7 +2,7 @@
 #ifndef COMP_TIMESTRUC_T_H
 #define COMP_TIMESTRUC_T_H
 
-#if defined(sun) || defined(__sun)
+#ifdef __sun
 #else
 typedef struct timespec timestruc_t;
 #endif
diff --git a/include/bsd/bsd.h b/include/bsd/bsd.h
index fdba250..92736d6 100644
--- a/include/bsd/bsd.h
+++ b/include/bsd/bsd.h
@@ -32,7 +32,7 @@
 
 #include <signal.h>
 
-#if defined(sun) || defined(__sun)
+#ifdef __sun
 
 #ifndef __cplusplus
 typedef void (*SIG_PF) (int);
diff --git a/include/mk/defs.h b/include/mk/defs.h
index a929e03..022dc88 100644
--- a/include/mk/defs.h
+++ b/include/mk/defs.h
@@ -294,7 +294,7 @@ extern	long int	hostid;
  * Declarations of system defined variables
  */
 /* On linux this variable is defined in 'signal.h' */
-#if defined(sun) || defined(__sun)
+#ifdef __sun
 extern	char		*sys_siglist[];
 #else
 #include <signal.h>
@@ -357,7 +357,7 @@ extern	wchar_t		*getmem_wc(register int size);
 #ifdef __cplusplus
 extern "C" {
 #endif
-#if defined(sun) || defined(__sun)
+#ifdef __sun
 extern	char		*getwd(char *);
 #endif
 #ifdef __cplusplus
diff --git a/lib/mksh/dosys.cc b/lib/mksh/dosys.cc
index 7c30a28..25cd550 100644
--- a/lib/mksh/dosys.cc
+++ b/lib/mksh/dosys.cc
@@ -93,7 +93,7 @@ redirect_io(char *stdout_file, char *stderr_file)
 {
 	int	i;
 
-#if defined(sun) || defined(__sun)
+#ifdef __sun
 	(void) closefrom(3);
 #else
         // XXX not available on Linux
diff --git a/lib/mksh/misc.cc b/lib/mksh/misc.cc
index db2cf29..b476b0b 100644
--- a/lib/mksh/misc.cc
+++ b/lib/mksh/misc.cc
@@ -272,28 +272,28 @@ void
 enable_interrupt(register void (*handler) (int))
 {
 	if (sigivalue != SIG_IGN) {
-#if defined(sun) || defined(__sun)
+#ifdef __sun
 		(void) bsd_signal(SIGINT, (SIG_PF) handler);
 #else
 		(void) bsd_signal(SIGINT, handler);
 #endif
 	}
 	if (sigqvalue != SIG_IGN) {
-#if defined(sun) || defined(__sun)
+#ifdef __sun
 		(void) bsd_signal(SIGQUIT, (SIG_PF) handler);
 #else
 		(void) bsd_signal(SIGQUIT, handler);
 #endif
 	}
 	if (sigtvalue != SIG_IGN) {
-#if defined(sun) || defined(__sun)
+#ifdef __sun
 		(void) bsd_signal(SIGTERM, (SIG_PF) handler);
 #else
 		(void) bsd_signal(SIGTERM, handler);
 #endif
 	}
 	if (sighvalue != SIG_IGN) {
-#if defined(sun) || defined(__sun)
+#ifdef __sun
 		(void) bsd_signal(SIGHUP, (SIG_PF) handler);
 #else
 		(void) bsd_signal(SIGHUP, handler);
diff --git a/lib/vroot/lock.cc b/lib/vroot/lock.cc
index d31cb5e..c70f84f 100644
--- a/lib/vroot/lock.cc
+++ b/lib/vroot/lock.cc
@@ -36,7 +36,7 @@
 #include <errno.h>			/* errno */
 #include <libintl.h>
 
-#if defined(sun) || defined(__sun)
+#ifdef __sun
 extern	char		*sys_errlist[];
 extern	int		sys_nerr;
 #endif