diff --git a/Build.sh b/Build.sh
index c58972c..518dd96 100644
--- a/Build.sh
+++ b/Build.sh
@@ -1,5 +1,5 @@
 #!/bin/sh
-# $MirOS: src/bin/mksh/Build.sh,v 1.50 2006/08/24 20:32:52 tg Exp $
+# $MirOS: src/bin/mksh/Build.sh,v 1.51 2006/08/26 20:30:27 tg Exp $
 #-
 # Environment: CC, CFLAGS, CPPFLAGS, LDFLAGS, LIBS, NROFF
 
@@ -111,6 +111,51 @@ if test x"$sigseen" = x:; then
 	done >signames.inc
 	test -s signames.inc || exit 1
 fi
+
+$e Scanning for functions...
+
+test 0 = "$HAVE_ARC4RANDOM" -o 0 = "$HAVE_ARC4RANDOM" ||
+{
+	$e ... arc4random
+	cat >scn.c <<-'EOF'
+		#include <stdlib.h>
+		int main() { arc4random(); return (0); }
+	EOF
+	$CC $CFLAGS $CPPFLAGS $LDFLAGS -Wno-error scn.c $LIBS
+	if test -e a.out -o -e a.exe; then
+		HAVE_ARC4RANDOM=1
+		$e "==> arc4random... yes"
+	else
+		HAVE_ARC4RANDOM=0
+		$e "==> arc4random... no"
+	fi
+	rm -f scn.c a.out a.exe
+}
+
+test 0 = "$HAVE_ARC4RANDOM_PUSH" -o 0 = "$HAVE_ARC4RANDOM_PUSH" ||
+if test 1 = "$HAVE_ARC4RANDOM"; then
+	$e ... arc4random_push
+	cat >scn.c <<-'EOF'
+		#include <stdlib.h>
+		int main() { arc4random_push(1); return (0); }
+	EOF
+	$CC $CFLAGS $CPPFLAGS $LDFLAGS -Wno-error scn.c $LIBS
+	if test -e a.out -o -e a.exe; then
+		HAVE_ARC4RANDOM_PUSH=1
+		$e "==> arc4random_push... yes"
+	else
+		HAVE_ARC4RANDOM_PUSH=0
+		$e "==> arc4random_push... no"
+	fi
+	rm -f scn.c a.out a.exe
+else
+	HAVE_ARC4RANDOM_PUSH=0
+fi
+
+$e ... done.
+CPPFLAGS="$CPPFLAGS -DHAVE_ARC4RANDOM=$HAVE_ARC4RANDOM \
+	-DHAVE_ARC4RANDOM_PUSH=$HAVE_ARC4RANDOM_PUSH"
+
 (v "cd '$srcdir' && exec $CC $CFLAGS -I'$curdir' $CPPFLAGS" \
     "$LDFLAGS $LDSTATIC -o '$curdir/mksh' $SRCS $LIBS") || exit 1
 test -x mksh || exit 1
diff --git a/Makefile b/Makefile
index 38d5896..bcf6dd0 100644
--- a/Makefile
+++ b/Makefile
@@ -1,8 +1,9 @@
-# $MirOS: src/bin/mksh/Makefile,v 1.11 2006/08/01 12:46:01 tg Exp $
+# $MirOS: src/bin/mksh/Makefile,v 1.12 2006/08/26 20:30:27 tg Exp $
 
 PROG=		mksh
 SRCS=		alloc.c edit.c eval.c exec.c expr.c funcs.c histrap.c \
 		jobs.c lex.c main.c misc.c shf.c syn.c tree.c var.c
+CPPFLAGS+=	-DHAVE_ARC4RANDOM -DHAVE_ARC4RANDOM_PUSH
 CDIAGFLAGS+=	-Wno-cast-qual
 
 LINKS+=		${BINDIR}/${PROG} ${BINDIR}/sh
diff --git a/check.t b/check.t
index a7f34eb..5ba4558 100644
--- a/check.t
+++ b/check.t
@@ -1,4 +1,4 @@
-# $MirOS: src/bin/mksh/check.t,v 1.61 2006/08/24 20:50:02 tg Exp $
+# $MirOS: src/bin/mksh/check.t,v 1.62 2006/08/26 20:30:27 tg Exp $
 # $OpenBSD: bksl-nl.t,v 1.2 2001/01/28 23:04:56 niklas Exp $
 # $OpenBSD: history.t,v 1.5 2001/01/28 23:04:56 niklas Exp $
 # $OpenBSD: read.t,v 1.3 2003/03/10 03:48:16 david Exp $
@@ -3872,5 +3872,5 @@ category: pdksh
 stdin:
 	echo $KSH_VERSION
 expected-stdout:
-	@(#)MIRBSD KSH R28 2006/08/24
+	@(#)MIRBSD KSH R28 2006/08/26
 ---
diff --git a/sh.h b/sh.h
index 7a1fb80..97adab6 100644
--- a/sh.h
+++ b/sh.h
@@ -8,8 +8,8 @@
 /*	$OpenBSD: c_test.h,v 1.4 2004/12/20 11:34:26 otto Exp $	*/
 /*	$OpenBSD: tty.h,v 1.5 2004/12/20 11:34:26 otto Exp $	*/
 
-#define MKSH_SH_H_ID "$MirOS: src/bin/mksh/sh.h,v 1.40 2006/08/24 20:35:40 tg Exp $"
-#define MKSH_VERSION "R28 2006/08/24"
+#define MKSH_SH_H_ID "$MirOS: src/bin/mksh/sh.h,v 1.41 2006/08/26 20:30:27 tg Exp $"
+#define MKSH_VERSION "R28 2006/08/26"
 
 #include <sys/param.h>
 
@@ -1342,21 +1342,3 @@ extern void tty_close(void);
 # undef EXTERN
 #endif
 #undef I__
-
-#ifndef HAVE_ARC4RANDOM
-#if defined(__gnu_linux__) || defined(__INTERIX) || defined(__sun__) \
-    || (defined(__NetBSD__) && (__NetBSD_Version__ < 106020000)) \
-    || defined(__CYGWIN__)
-#define HAVE_ARC4RANDOM 0
-#else
-#define HAVE_ARC4RANDOM 1
-#endif
-#endif
-
-#ifndef HAVE_ARC4RANDOM_PUSH
-#if defined(__MirBSD__) && (MirBSD >= 0x07AD)
-#define HAVE_ARC4RANDOM_PUSH 1
-#else
-#define HAVE_ARC4RANDOM_PUSH 0
-#endif
-#endif