diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3f6386957..6899c565c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -94,9 +94,25 @@ option( BUILD_SCHEMA_TESTING "Enable schema-validation-tests" ON )
 # all the implementations are enabled (this just means they are
 # **available** to `settings.conf`, not that they are used).
 #
-# Currently, only USE_services is in use (to pick only one of the two
-# modules, systemd or openrc).
+# To explicitly disable a set of modules, set USE_<foo>=none
+# (e.g. the literal string none), which won't match any of the
+# modules but is handled specially. This is the default for
+# USE_os, which are modules for specialty non-Linux distributions.
+#
+# The following USE_* functionalities are available:
+#  - *services* picks one of the two service-configuration modules,
+#    for either systemd or openrc. This defaults to empty so that
+#    **both** modules are available.
+#  - *os* picks an OS-specific module for things-that-are-not-Linux.
+#    It is generally discouraged to use this unless your distro is
+#    completely unable to use standard Linux tools for configuration.
+#    This defaults to *none* so that nothing gets picked up and nothing
+#    is packaged -- you must explicitly set it to empty to get all of
+#    the modules, but that hardly makes sense. Note, too that there
+#    are no os-* modules shipped with Calamares. They live in the
+#    *calamares-extensions* repository.
 set( USE_services "" CACHE STRING "Select the services module to use" )
+set( USE_os "none" CACHE STRING "Select the OS-specific module to include" )
 
 ### Calamares application info
 #
diff --git a/src/modules/CMakeLists.txt b/src/modules/CMakeLists.txt
index 08e5a8520..d49a4c0c0 100644
--- a/src/modules/CMakeLists.txt
+++ b/src/modules/CMakeLists.txt
@@ -59,6 +59,9 @@ calamares_explain_skipped_modules( ${LIST_SKIPPED_MODULES} )
 
 foreach( _category ${_use_categories} )
     list( FIND _found_categories ${_category} _found )
+    if ( ${USE_${_category}} STREQUAL "none" )
+        set( _found 0 )
+    endif()
     if ( _found EQUAL -1 )
         message( FATAL_ERROR "USE_${_category} is set to ${USE_${_category}} and no module matches." )
     endif()