diff --git a/package/fluxbox/Config.in b/package/fluxbox/Config.in
index cb4d76feb..ab479a9f6 100644
--- a/package/fluxbox/Config.in
+++ b/package/fluxbox/Config.in
@@ -2,6 +2,7 @@ config BR2_PACKAGE_FLUXBOX
 	bool "fluxbox"
 	depends on BR2_PACKAGE_XORG7
 	depends on BR2_INSTALL_LIBSTDCPP
+	depends on BR2_USE_MMU # fork()
 	select BR2_PACKAGE_XLIB_LIBX11
 	# Runtime dependency, needed by startup script
 	select BR2_PACKAGE_XAPP_XMODMAP
@@ -11,4 +12,5 @@ config BR2_PACKAGE_FLUXBOX
 	  http://fluxbox.org
 
 comment "fluxbox needs a toolchain w/ C++"
+	depends on BR2_USE_MMU
 	depends on BR2_PACKAGE_XORG7 && !BR2_INSTALL_LIBSTDCPP