diff --git a/package/collectd/Config.in b/package/collectd/Config.in
index fe520f8ce9..74419f6e8e 100644
--- a/package/collectd/Config.in
+++ b/package/collectd/Config.in
@@ -212,7 +212,8 @@ config BR2_PACKAGE_COLLECTD_MEMORY
 
 config BR2_PACKAGE_COLLECTD_MYSQL
 	bool "mysql"
-	depends on BR2_INSTALL_LIBSTDCPP
+	depends on BR2_INSTALL_LIBSTDCPP # mysql
+	depends on BR2_USE_MMU # mysql
 	select BR2_PACKAGE_MYSQL_CLIENT
 	help
 	  Connects to a MySQL database and issues a "show status" command.
diff --git a/package/mysql_client/Config.in b/package/mysql_client/Config.in
index f07fdb4ce1..970b9b98cc 100644
--- a/package/mysql_client/Config.in
+++ b/package/mysql_client/Config.in
@@ -1,6 +1,7 @@
 config BR2_PACKAGE_MYSQL_CLIENT
 	bool "MySQL client"
 	depends on BR2_INSTALL_LIBSTDCPP
+	depends on BR2_USE_MMU # fork()
 	select BR2_PACKAGE_NCURSES
 	select BR2_PACKAGE_READLINE
 	help
diff --git a/package/poco/Config.in b/package/poco/Config.in
index 36d8de91f1..20a8f2dfa5 100644
--- a/package/poco/Config.in
+++ b/package/poco/Config.in
@@ -51,6 +51,7 @@ config BR2_PACKAGE_POCO_DATA_SQLITE
 
 config BR2_PACKAGE_POCO_DATA_MYSQL
 	bool "mysql"
+	depends on BR2_USE_MMU # mysql
 	select BR2_PACKAGE_POCO_DATA
 	select BR2_PACKAGE_MYSQL_CLIENT