diff --git a/tools/test/stress2/misc/fdatasync.sh b/tools/test/stress2/misc/fdatasync.sh
--- a/tools/test/stress2/misc/fdatasync.sh
+++ b/tools/test/stress2/misc/fdatasync.sh
@@ -178,7 +178,7 @@
 
 	if ((pw = getpwnam("nobody")) == NULL)
 		err(1, "failed to resolve nobody");
-	if (setgroups(1, &pw->pw_gid) ||
+	if (setgroups(0, NULL) ||
 	    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 	    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 		err(1, "Can't drop privileges to \"nobody\"");
diff --git a/tools/test/stress2/misc/fdatasync2.sh b/tools/test/stress2/misc/fdatasync2.sh
--- a/tools/test/stress2/misc/fdatasync2.sh
+++ b/tools/test/stress2/misc/fdatasync2.sh
@@ -177,7 +177,7 @@
 
 	if ((pw = getpwnam("nobody")) == NULL)
 		err(1, "failed to resolve nobody");
-	if (setgroups(1, &pw->pw_gid) ||
+	if (setgroups(0, NULL) ||
 	    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 	    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 		err(1, "Can't drop privileges to \"nobody\"");
diff --git a/tools/test/stress2/misc/fifo2.sh b/tools/test/stress2/misc/fifo2.sh
--- a/tools/test/stress2/misc/fifo2.sh
+++ b/tools/test/stress2/misc/fifo2.sh
@@ -167,7 +167,7 @@
 	if ((pw = getpwnam("nobody")) == NULL)
 		err(1, "no such user: nobody");
 
-	if (setgroups(1, &pw->pw_gid) ||
+	if (setgroups(0, NULL) ||
 	    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 	    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 		err(1, "Can't drop privileges to \"nobody\"");
diff --git a/tools/test/stress2/misc/ftruncate.sh b/tools/test/stress2/misc/ftruncate.sh
--- a/tools/test/stress2/misc/ftruncate.sh
+++ b/tools/test/stress2/misc/ftruncate.sh
@@ -170,7 +170,7 @@
 
 	if ((pw = getpwnam("nobody")) == NULL)
 		err(1, "failed to resolve nobody");
-	if (setgroups(1, &pw->pw_gid) ||
+	if (setgroups(0, NULL) ||
 	    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 	    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 		err(1, "Can't drop privileges to \"nobody\"");
diff --git a/tools/test/stress2/misc/ftruncate2.sh b/tools/test/stress2/misc/ftruncate2.sh
--- a/tools/test/stress2/misc/ftruncate2.sh
+++ b/tools/test/stress2/misc/ftruncate2.sh
@@ -185,7 +185,7 @@
 
 	if ((pw = getpwnam("nobody")) == NULL)
 		err(1, "failed to resolve nobody");
-	if (setgroups(1, &pw->pw_gid) ||
+	if (setgroups(0, NULL) ||
 	    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 	    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 		err(1, "Can't drop privileges to \"nobody\"");
diff --git a/tools/test/stress2/misc/kevent7.sh b/tools/test/stress2/misc/kevent7.sh
--- a/tools/test/stress2/misc/kevent7.sh
+++ b/tools/test/stress2/misc/kevent7.sh
@@ -236,7 +236,7 @@
 	if ((pw = getpwnam("nobody")) == NULL)
 		err(1, "no such user: nobody");
 
-	if (setgroups(1, &pw->pw_gid) ||
+	if (setgroups(0, NULL) ||
 	    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 	    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 		err(1, "Can't drop privileges to \"nobody\"");
diff --git a/tools/test/stress2/misc/killpg.sh b/tools/test/stress2/misc/killpg.sh
--- a/tools/test/stress2/misc/killpg.sh
+++ b/tools/test/stress2/misc/killpg.sh
@@ -113,7 +113,7 @@
 	if ((pw = getpwnam("nobody")) == NULL)
 		err(1, "no such user: nobody");
 
-	if (setgroups(1, &pw->pw_gid) ||
+	if (setgroups(0, NULL) ||
 	    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 	    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 		err(1, "Can't drop privileges to \"nobody\"");
diff --git a/tools/test/stress2/misc/killpg2.sh b/tools/test/stress2/misc/killpg2.sh
--- a/tools/test/stress2/misc/killpg2.sh
+++ b/tools/test/stress2/misc/killpg2.sh
@@ -77,7 +77,7 @@
 	if ((pw = getpwnam("TUSER")) == NULL)
 		err(1, "no such user: TUSER");
 
-	if (setgroups(1, &pw->pw_gid) ||
+	if (setgroups(0, NULL) ||
 	    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 	    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 		err(1, "Can't drop privileges to \"TUSER\"");
diff --git a/tools/test/stress2/misc/killpg3.sh b/tools/test/stress2/misc/killpg3.sh
--- a/tools/test/stress2/misc/killpg3.sh
+++ b/tools/test/stress2/misc/killpg3.sh
@@ -109,7 +109,7 @@
 	if ((pw = getpwnam("TUSER")) == NULL)
 		err(1, "no such user: TUSER");
 
-	if (setgroups(1, &pw->pw_gid) ||
+	if (setgroups(0, NULL) ||
 	    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 	    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 		err(1, "Can't drop privileges to \"TUSER\"");
diff --git a/tools/test/stress2/misc/maxproc.sh b/tools/test/stress2/misc/maxproc.sh
--- a/tools/test/stress2/misc/maxproc.sh
+++ b/tools/test/stress2/misc/maxproc.sh
@@ -103,7 +103,7 @@
 			err(1, "no such user: nobody");
 
 		if (priv == 0) {
-			if (setgroups(1, &pw->pw_gid) ||
+			if (setgroups(0, NULL) ||
 			    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 			    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 				err(1, "Can't drop privileges to \"nobody\"");
diff --git a/tools/test/stress2/misc/mlockall3.sh b/tools/test/stress2/misc/mlockall3.sh
--- a/tools/test/stress2/misc/mlockall3.sh
+++ b/tools/test/stress2/misc/mlockall3.sh
@@ -130,7 +130,7 @@
 	if ((pw = getpwnam("nobody")) == NULL)
 		err(1, "no such user: nobody");
 
-	if (setgroups(1, &pw->pw_gid) ||
+	if (setgroups(0, NULL) ||
 	    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 	    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 		err(1, "Can't drop privileges to \"nobody\"");
diff --git a/tools/test/stress2/misc/mlockall7.sh b/tools/test/stress2/misc/mlockall7.sh
--- a/tools/test/stress2/misc/mlockall7.sh
+++ b/tools/test/stress2/misc/mlockall7.sh
@@ -179,7 +179,7 @@
 	maxlock = maxl;
 	if ((pw = getpwnam("nobody")) == NULL)
 		err(1, "failed to resolve nobody");
-	if (setgroups(1, &pw->pw_gid) ||
+	if (setgroups(0, NULL) ||
 	    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 	    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 		err(1, "Can't drop privileges to \"nobody\"");
diff --git a/tools/test/stress2/misc/mountu.sh b/tools/test/stress2/misc/mountu.sh
--- a/tools/test/stress2/misc/mountu.sh
+++ b/tools/test/stress2/misc/mountu.sh
@@ -241,7 +241,7 @@
 	if ((pw = getpwnam("nobody")) == NULL)
 		err(1, "no such user: nobody");
 
-	if (setgroups(1, &pw->pw_gid) ||
+	if (setgroups(0, NULL) ||
 	    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 	    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 		err(1, "Can't drop privileges to \"nobody\"");
diff --git a/tools/test/stress2/misc/msync.sh b/tools/test/stress2/misc/msync.sh
--- a/tools/test/stress2/misc/msync.sh
+++ b/tools/test/stress2/misc/msync.sh
@@ -166,7 +166,7 @@
 	if ((pw = getpwnam("nobody")) == NULL)
 		err(1, "no such user: nobody");
 
-	if (setgroups(1, &pw->pw_gid) ||
+	if (setgroups(0, NULL) ||
 	    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 	    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 		err(1, "Can't drop privileges to \"nobody\"");
diff --git a/tools/test/stress2/misc/pread.sh b/tools/test/stress2/misc/pread.sh
--- a/tools/test/stress2/misc/pread.sh
+++ b/tools/test/stress2/misc/pread.sh
@@ -170,7 +170,7 @@
         if ((pw = getpwnam("nobody")) == NULL)
                 err(1, "no such user: nobody");
 
-        if (setgroups(1, &pw->pw_gid) ||
+        if (setgroups(0, NULL) ||
             setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
             seteuid(pw->pw_uid) || setuid(pw->pw_uid))
                 err(1, "Can't drop privileges to \"nobody\"");
diff --git a/tools/test/stress2/misc/sched.sh b/tools/test/stress2/misc/sched.sh
--- a/tools/test/stress2/misc/sched.sh
+++ b/tools/test/stress2/misc/sched.sh
@@ -107,7 +107,7 @@
 
 	if ((pw = getpwnam("nobody")) == NULL)
 		err(1, "no such user: nobody");
-	if (setgroups(1, &pw->pw_gid) ||
+	if (setgroups(0, NULL) ||
 	    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 	    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 		err(1, "Can't drop privileges to \"nobody\"");
diff --git a/tools/test/stress2/misc/sigreturn3.sh b/tools/test/stress2/misc/sigreturn3.sh
--- a/tools/test/stress2/misc/sigreturn3.sh
+++ b/tools/test/stress2/misc/sigreturn3.sh
@@ -121,7 +121,7 @@
 		fprintf(stderr, "Running syscall4 as root for %s.\n",
 				argv[1]);
 	else {
-		if (setgroups(1, &pw->pw_gid) ||
+		if (setgroups(0, NULL) ||
 		    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 		    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 			err(1, "Can't drop privileges to \"nobody\"");
diff --git a/tools/test/stress2/misc/sigreturn4.sh b/tools/test/stress2/misc/sigreturn4.sh
--- a/tools/test/stress2/misc/sigreturn4.sh
+++ b/tools/test/stress2/misc/sigreturn4.sh
@@ -147,7 +147,7 @@
 		fprintf(stderr, "Running sigreturn4 as root for %s.\n",
 				argv[1]);
 	else {
-		if (setgroups(1, &pw->pw_gid) ||
+		if (setgroups(0, NULL) ||
 		    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 		    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 			err(1, "Can't drop privileges to \"nobody\"");
diff --git a/tools/test/stress2/misc/syscall4.sh b/tools/test/stress2/misc/syscall4.sh
--- a/tools/test/stress2/misc/syscall4.sh
+++ b/tools/test/stress2/misc/syscall4.sh
@@ -318,7 +318,7 @@
 		fprintf(stderr, "Running syscall4 as root for %s.\n",
 				argv[1]);
 	else {
-		if (setgroups(1, &pw->pw_gid) ||
+		if (setgroups(0, NULL) ||
 		    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 		    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 			err(1, "Can't drop privileges to \"nobody\"");
diff --git a/tools/test/stress2/misc/tmpfs16.sh b/tools/test/stress2/misc/tmpfs16.sh
--- a/tools/test/stress2/misc/tmpfs16.sh
+++ b/tools/test/stress2/misc/tmpfs16.sh
@@ -181,7 +181,7 @@
 
 	if ((pw = getpwnam("nobody")) == NULL)
 		err(1, "failed to resolve nobody");
-	if (setgroups(1, &pw->pw_gid) ||
+	if (setgroups(0, NULL) ||
 	    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
 	    seteuid(pw->pw_uid) || setuid(pw->pw_uid))
 		err(1, "Can't drop privileges to \"nobody\"");