diff --git a/package/libassuan/Config.in b/package/libassuan/Config.in
index e97ebdcdd..46101451c 100644
--- a/package/libassuan/Config.in
+++ b/package/libassuan/Config.in
@@ -1,5 +1,6 @@
 config BR2_PACKAGE_LIBASSUAN
 	bool "libassuan"
+	depends on BR2_USE_MMU # fork()
 	select BR2_PACKAGE_LIBGPG_ERROR
 	help
 	  Libassuan is a small library implementing the so-called
diff --git a/package/libgpgme/Config.in b/package/libgpgme/Config.in
index f97a3fe89..a303bfae8 100644
--- a/package/libgpgme/Config.in
+++ b/package/libgpgme/Config.in
@@ -1,5 +1,6 @@
 config BR2_PACKAGE_LIBGPGME
 	bool "libgpgme"
+	depends on BR2_USE_MMU # libassuan
 	#gnupg is not needed to build, but at runtime.
 	select BR2_PACKAGE_GNUPG
 	select BR2_PACKAGE_LIBGPG_ERROR
diff --git a/package/opkg/Config.in b/package/opkg/Config.in
index 5906210e8..afc13f2c1 100644
--- a/package/opkg/Config.in
+++ b/package/opkg/Config.in
@@ -1,5 +1,6 @@
 config BR2_PACKAGE_OPKG
 	bool "opkg"
+	depends on BR2_USE_MMU # fork()
 	help
 	  Opkg is a lightweight package management system, based on ipkg. It is
 	  written in C and resembles apt/dpkg in operation. It is intended for