diff --git a/src/cmd/ksh93/sh/args.c b/src/cmd/ksh93/sh/args.c
index a4a11012d..70bcabea6 100644
--- a/src/cmd/ksh93/sh/args.c
+++ b/src/cmd/ksh93/sh/args.c
@@ -302,6 +302,8 @@ int sh_argopts(int argc,register char *argv[], void *context)
 		}
 		else
 		{
+			if ((o == SH_RESTRICTED) && sh_isoption(SH_RESTRICTED))
+				errormsg(SH_DICT,ERROR_exit(1),e_restricted,"r"); /* set -r cannot be unset */
 			if(o==SH_XTRACE)
 				trace = 0;
 			off_option(&newflags,o);
diff --git a/src/cmd/ksh93/tests/restricted.sh b/src/cmd/ksh93/tests/restricted.sh
index abf33cc82..eb32c01bb 100755
--- a/src/cmd/ksh93/tests/restricted.sh
+++ b/src/cmd/ksh93/tests/restricted.sh
@@ -87,4 +87,10 @@ for i in PATH ENV FPATH
 do	check_restricted  "function foo { typeset $i=foobar;};foo" || err_exit "$i can be changed in function by using typeset"
 done
 
+# ======
+# `set +r` and `set +o restricted` should not unset the restricted option
+check_restricted 'set +r' 2> /dev/null || err_exit '`set +r` unsets the restricted option'
+check_restricted 'set +o restricted' 2> /dev/null || err_exit '`set +o restricted` unsets the restricted option'
+
+# ======
 exit $((Errors<125?Errors:125))