diff --git a/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/usdt/tst.multiprov.ksh b/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/usdt/tst.multiprov.ksh
index 9620b97cb019..c8f0d1e5f8c0 100644
--- a/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/usdt/tst.multiprov.ksh
+++ b/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/usdt/tst.multiprov.ksh
@@ -1,106 +1,107 @@
 #
 # CDDL HEADER START
 #
 # The contents of this file are subject to the terms of the
 # Common Development and Distribution License (the "License").
 # You may not use this file except in compliance with the License.
 #
 # You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 # or http://www.opensolaris.org/os/licensing.
 # See the License for the specific language governing permissions
 # and limitations under the License.
 #
 # When distributing Covered Code, include this CDDL HEADER in each
 # file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 # If applicable, add the following below this CDDL HEADER, with the
 # fields enclosed by brackets "[]" replaced with your own identifying
 # information: Portions Copyright [yyyy] [name of copyright owner]
 #
 # CDDL HEADER END
 #
 
 #
 # Copyright (c) 2013, Joyent, Inc. All rights reserved.
 #
 
 if [ $# != 1 ]; then
 	echo expected one argument: '<'dtrace-path'>'
 	exit 2
 fi
 
 dtrace=$1
 DIR=/var/tmp/dtest.$$
 
 mkdir $DIR
 cd $DIR
 
 echo '#pragma D option quiet' > test.d
 echo '#pragma D option aggsortkey' >> test.d
 
 cat > test.c <<EOF
 #include <unistd.h>
 
-void
-main()
+int
+main(void)
 {
 EOF
 
 objs=
 
 for oogle in doogle bagnoogle; do
 	cat > $oogle.c <<EOF
 #include <sys/sdt.h>
 
 void
-$oogle()
+$oogle(void)
 {
 	DTRACE_PROBE($oogle, knows);
 }
 EOF
 
 	cat > $oogle.d <<EOF
 provider $oogle {
 	probe knows();
 };
 EOF
 
 	cc -c $oogle.c
 
 	if [ $? -ne 0 ]; then
 		print -u2 "failed to compile $oogle.c"
 		exit 1
 	fi
 
 	$dtrace -G -s $oogle.d $oogle.o -o $oogle.d.o
 
 	if [ $? -ne 0 ]; then
 		print -u2 "failed to process $oogle.d"
 		exit 1
 	fi
 
 	objs="$objs $oogle.o $oogle.d.o"
+	echo "extern void $oogle(void);" >> test.c
 	echo $oogle'();' >> test.c
 	echo $oogle'$target:::{@[probefunc] = count()}' >> test.d
 done
 
 echo "}" >> test.c
 
 echo 'END{printa("%-10s %@d\\n", @)}' >> test.d
 
 cc -o test test.c $objs
 
 if [ $? -ne 0 ]; then
 	print -u2 "failed to compile test.c"
 	exit 1
 fi
 
 $dtrace -s ./test.d -Zc ./test
 
 if [ $? -ne 0 ]; then
 	print -u2 "failed to execute test"
 	exit 1
 fi
 
 cd /
 rm -rf $DIR
 exit 0
diff --git a/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/usdt/tst.sameprovmulti.ksh b/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/usdt/tst.sameprovmulti.ksh
index 2e404f4b8df6..4dd54f3fb633 100644
--- a/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/usdt/tst.sameprovmulti.ksh
+++ b/cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/usdt/tst.sameprovmulti.ksh
@@ -1,99 +1,100 @@
 #
 # This file and its contents are supplied under the terms of the
 # Common Development and Distribution License ("CDDL"), version 1.0.
 # You may only use this file in accordance with the terms of version
 # 1.0 of the CDDL.
 #
 # A full copy of the text of the CDDL should have accompanied this
 # source.  A copy of the CDDL is also available via the Internet at
 # http://www.illumos.org/license/CDDL.
 #
 
 #
 # Copyright (c) 2015, Joyent, Inc. All rights reserved.
 #
 
 #
 # This test assures that we can have the same provider name across multiple
 # probe definitions, and that the result will be the union of those
 # definitions.  In particular, libusdt depends on this when (for example)
 # node modules that create a provider are loaded multiple times due to
 # being included by different modules.
 #
 
 if [ $# != 1 ]; then
 	echo expected one argument: '<'dtrace-path'>'
 	exit 2
 fi
 
 dtrace=$1
 DIR=/var/tmp/dtest.$$
 
 mkdir $DIR
 cd $DIR
 
 cat > test.c <<EOF
 #include <unistd.h>
 
-void
-main()
+int
+main(void)
 {
 EOF
 
 objs=
 
 for oogle in bagnoogle stalloogle cockoogle; do
 	cat > $oogle.c <<EOF
 #include <sys/sdt.h>
 
 void
 $oogle()
 {
 	DTRACE_PROBE(doogle, $oogle);
 }
 EOF
 
 	cat > $oogle.d <<EOF
 provider doogle {
 	probe $oogle();
 };
 EOF
 
 	cc -c $oogle.c
 
 	if [ $? -ne 0 ]; then
 		print -u2 "failed to compile $oogle.c"
 		exit 1
 	fi
 
 	$dtrace -G -s $oogle.d $oogle.o -o $oogle.d.o
 
 	if [ $? -ne 0 ]; then
 		print -u2 "failed to process $oogle.d"
 		exit 1
 	fi
 
 	objs="$objs $oogle.o $oogle.d.o"
+	echo "extern void $oogle(void);" >> test.c
 	echo $oogle'();' >> test.c
 done
 
 echo "}" >> test.c
 
 cc -o test test.c $objs
 
 if [ $? -ne 0 ]; then
 	print -u2 "failed to compile test.c"
 	exit 1
 fi
 
 $dtrace -n 'doogle$target:::{@[probename] = count()}' \
     -n 'END{printa("%-10s %@d\n", @)}' -x quiet -x aggsortkey -Zc ./test
 
 if [ $? -ne 0 ]; then
 	print -u2 "failed to execute test"
 	exit 1
 fi
 
 cd /
 rm -rf $DIR
 exit 0