diff --git a/src/cmd/mk/shell.c b/src/cmd/mk/shell.c
index 8c15ec21..3e10146f 100644
--- a/src/cmd/mk/shell.c
+++ b/src/cmd/mk/shell.c
@@ -41,6 +41,8 @@ setshell(Word *w)
 void
 initshell(void)
 {
+	if(getenv("FORCERCFORMK") != nil)
+		shelldefault = &rcshell;
 	shellcmd = stow(shelldefault->name);
 	shellt = shelldefault;
 	setvar("MKSHELL", shellcmd);