diff --git a/bin/ps/extern.h b/bin/ps/extern.h
index dedac7ee5921..55796699d435 100644
--- a/bin/ps/extern.h
+++ b/bin/ps/extern.h
@@ -41,7 +41,7 @@ struct varent;
 
 extern fixpt_t ccpu;
 extern int eval, fscale, mempages, nlistread, rawcpu, cflag;
-extern int sumrusage, termwidth, totwidth;
+extern int sumrusage, termwidth, totwidth, use_ampm;
 extern VAR var[];
 extern VARENT *vhead;
 
diff --git a/bin/ps/print.c b/bin/ps/print.c
index 72d96cfa41e9..37d03a382821 100644
--- a/bin/ps/print.c
+++ b/bin/ps/print.c
@@ -366,9 +366,11 @@ started(k, ve)
 	if (!now)
 		(void)time(&now);
 	if (now - k->ki_p->ki_start.tv_sec < 24 * 3600) {
-		(void)strftime(buf, sizeof(buf) - 1, "%l:%M%p", tp);
+		(void)strftime(buf, sizeof(buf) - 1,
+		use_ampm ? "%l:%M%p" : "%k:%M  ", tp);
 	} else if (now - k->ki_p->ki_start.tv_sec < 7 * 86400) {
-		(void)strftime(buf, sizeof(buf) - 1, "%a%I%p", tp);
+		(void)strftime(buf, sizeof(buf) - 1,
+		use_ampm ? "%a%I%p" : "%a%H  ", tp);
 	} else
 		(void)strftime(buf, sizeof(buf) - 1, "%e%b%y", tp);
 	(void)printf("%-*s", v->width, buf);
diff --git a/bin/ps/ps.c b/bin/ps/ps.c
index 324ff6bbff16..7d5aaeebbd4a 100644
--- a/bin/ps/ps.c
+++ b/bin/ps/ps.c
@@ -58,14 +58,15 @@ static const char rcsid[] =
 #include <errno.h>
 #include <fcntl.h>
 #include <kvm.h>
+#include <langinfo.h>
 #include <limits.h>
+#include <locale.h>
 #include <nlist.h>
 #include <paths.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
-#include <locale.h>
 #include <pwd.h>
 #include <utmp.h>
 
@@ -82,6 +83,7 @@ int	rawcpu;			/* -C */
 int	sumrusage;		/* -S */
 int	termwidth;		/* width of screen (0 == infinity) */
 int	totwidth;		/* calculated width of requested variables */
+int	use_ampm;		/* use AM/PM time */
 
 static int needuser, needcomm, needenv;
 #if defined(LAZY_PS)
@@ -129,6 +131,7 @@ main(argc, argv)
 	char *nlistf, *memf, *swapf, errbuf[_POSIX2_LINE_MAX];
 
 	(void) setlocale(LC_ALL, "");
+	use_ampm = (*nl_langinfo(T_FMT_AMPM) != '\0');
 
 	if ((ioctl(STDOUT_FILENO, TIOCGWINSZ, (char *)&ws) == -1 &&
 	     ioctl(STDERR_FILENO, TIOCGWINSZ, (char *)&ws) == -1 &&