diff --git a/kernel/uid16.c b/kernel/uid16.c
index aa25605..187e2a4 100644
--- a/kernel/uid16.c
+++ b/kernel/uid16.c
@@ -20,43 +20,67 @@
 
 asmlinkage long sys_chown16(const char __user * filename, old_uid_t user, old_gid_t group)
 {
-	return sys_chown(filename, low2highuid(user), low2highgid(group));
+	long ret = sys_chown(filename, low2highuid(user), low2highgid(group));
+	/* avoid REGPARM breakage on x86: */
+	prevent_tail_call(ret);
+	return ret;
 }
 
 asmlinkage long sys_lchown16(const char __user * filename, old_uid_t user, old_gid_t group)
 {
-	return sys_lchown(filename, low2highuid(user), low2highgid(group));
+	long ret = sys_lchown(filename, low2highuid(user), low2highgid(group));
+	/* avoid REGPARM breakage on x86: */
+	prevent_tail_call(ret);
+	return ret;
 }
 
 asmlinkage long sys_fchown16(unsigned int fd, old_uid_t user, old_gid_t group)
 {
-	return sys_fchown(fd, low2highuid(user), low2highgid(group));
+	long ret = sys_fchown(fd, low2highuid(user), low2highgid(group));
+	/* avoid REGPARM breakage on x86: */
+	prevent_tail_call(ret);
+	return ret;
 }
 
 asmlinkage long sys_setregid16(old_gid_t rgid, old_gid_t egid)
 {
-	return sys_setregid(low2highgid(rgid), low2highgid(egid));
+	long ret = sys_setregid(low2highgid(rgid), low2highgid(egid));
+	/* avoid REGPARM breakage on x86: */
+	prevent_tail_call(ret);
+	return ret;
 }
 
 asmlinkage long sys_setgid16(old_gid_t gid)
 {
-	return sys_setgid(low2highgid(gid));
+	long ret = sys_setgid(low2highgid(gid));
+	/* avoid REGPARM breakage on x86: */
+	prevent_tail_call(ret);
+	return ret;
 }
 
 asmlinkage long sys_setreuid16(old_uid_t ruid, old_uid_t euid)
 {
-	return sys_setreuid(low2highuid(ruid), low2highuid(euid));
+	long ret = sys_setreuid(low2highuid(ruid), low2highuid(euid));
+	/* avoid REGPARM breakage on x86: */
+	prevent_tail_call(ret);
+	return ret;
 }
 
 asmlinkage long sys_setuid16(old_uid_t uid)
 {
-	return sys_setuid(low2highuid(uid));
+	long ret = sys_setuid(low2highuid(uid));
+	/* avoid REGPARM breakage on x86: */
+	prevent_tail_call(ret);
+	return ret;
 }
 
 asmlinkage long sys_setresuid16(old_uid_t ruid, old_uid_t euid, old_uid_t suid)
 {
-	return sys_setresuid(low2highuid(ruid), low2highuid(euid),
-		low2highuid(suid));
+	long ret = sys_setresuid(low2highuid(ruid), low2highuid(euid),
+				 low2highuid(suid));
+	/* avoid REGPARM breakage on x86: */
+	prevent_tail_call(ret);
+	return ret;
 }
 
 asmlinkage long sys_getresuid16(old_uid_t __user *ruid, old_uid_t __user *euid, old_uid_t __user *suid)
@@ -72,8 +96,11 @@
 
 asmlinkage long sys_setresgid16(old_gid_t rgid, old_gid_t egid, old_gid_t sgid)
 {
-	return sys_setresgid(low2highgid(rgid), low2highgid(egid),
-		low2highgid(sgid));
+	long ret = sys_setresgid(low2highgid(rgid), low2highgid(egid),
+				 low2highgid(sgid));
+	/* avoid REGPARM breakage on x86: */
+	prevent_tail_call(ret);
+	return ret;
 }
 
 asmlinkage long sys_getresgid16(old_gid_t __user *rgid, old_gid_t __user *egid, old_gid_t __user *sgid)
@@ -89,12 +116,18 @@
 
 asmlinkage long sys_setfsuid16(old_uid_t uid)
 {
-	return sys_setfsuid(low2highuid(uid));
+	long ret = sys_setfsuid(low2highuid(uid));
+	/* avoid REGPARM breakage on x86: */
+	prevent_tail_call(ret);
+	return ret;
 }
 
 asmlinkage long sys_setfsgid16(old_gid_t gid)
 {
-	return sys_setfsgid(low2highgid(gid));
+	long ret = sys_setfsgid(low2highgid(gid));
+	/* avoid REGPARM breakage on x86: */
+	prevent_tail_call(ret);
+	return ret;
 }
 
 static int groups16_to_user(old_gid_t __user *grouplist,