diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index a0a0d78b7..74b861281 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -57,16 +57,8 @@ bool BasicDerivation::isBuiltin() const
 bool BasicDerivation::canBuildLocally() const
 {
     return platform == settings.thisSystem
-        || isBuiltin()
-#if __linux__
-        || (platform == "i686-linux" && settings.thisSystem == "x86_64-linux")
-        || (platform == "armv6l-linux" && settings.thisSystem == "armv7l-linux")
-        || (platform == "armv5tel-linux" && (settings.thisSystem == "armv7l-linux" || settings.thisSystem == "armv6l-linux"))
-#elif __FreeBSD__
-        || (platform == "i686-linux" && settings.thisSystem == "x86_64-freebsd")
-        || (platform == "i686-linux" && settings.thisSystem == "i686-freebsd")
-#endif
-        ;
+        || settings.extraPlatforms.get().count(platform) > 0
+        || isBuiltin();
 }
 
 
diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index dd01f832d..b382da01e 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -295,6 +295,9 @@ public:
         "Nix store has a valid signature (that is, one signed using a key "
         "listed in 'trusted-public-keys'."};
 
+    Setting<StringSet> extraPlatforms{this, StringSet{}, "build-extra-platforms",
+        "Additional platforms that can be built on the local system, e.g. using qemu-user."};
+
     Setting<Strings> substituters{this,
         nixStore == "/nix/store" ? Strings{"https://cache.nixos.org/"} : Strings(),
         "substituters",