diff --git a/package/rtty/Config.in b/package/rtty/Config.in
index badb329d3e..198d465713 100644
--- a/package/rtty/Config.in
+++ b/package/rtty/Config.in
@@ -1,5 +1,6 @@
 config BR2_PACKAGE_RTTY
 	bool "rtty"
+	depends on BR2_USE_MMU # fork()
 	select BR2_PACKAGE_LIBEV
 	help
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