diff --git a/package/x11r7/xapp_xsm/Config.in b/package/x11r7/xapp_xsm/Config.in
index d06dc6c399..88f20cf65e 100644
--- a/package/x11r7/xapp_xsm/Config.in
+++ b/package/x11r7/xapp_xsm/Config.in
@@ -1,5 +1,6 @@
 config BR2_PACKAGE_XAPP_XSM
 	bool "xsm"
+	depends on BR2_USE_MMU # fork()
 	select BR2_PACKAGE_XLIB_LIBXAW
 	help
 	  X Session Manager