diff --git a/.version b/.version
index bcec02eeb96..0958964f67a 100644
--- a/.version
+++ b/.version
@@ -1 +1 @@
-2.30.1
+2.30.2
diff --git a/nix-meson-build-support/default-system-cpu/meson.build b/nix-meson-build-support/default-system-cpu/meson.build
new file mode 100644
index 00000000000..4a0e89e10c8
--- /dev/null
+++ b/nix-meson-build-support/default-system-cpu/meson.build
@@ -0,0 +1,10 @@
+powerpc_system_cpus = [ 'ppc64', 'ppc' ]
+
+nix_system_cpu = {'ppc64' : 'powerpc64', 'ppc' : 'powerpc', 'x86' : 'i686'}.get(
+  host_machine.cpu_family(),
+  host_machine.cpu_family(),
+)
+
+if powerpc_system_cpus.contains(host_machine.cpu_family()) and host_machine.endian() == 'little'
+  nix_system_cpu += 'le'
+endif
diff --git a/src/libstore/meson.build b/src/libstore/meson.build
index 2aff1729077..fe705a35e1e 100644
--- a/src/libstore/meson.build
+++ b/src/libstore/meson.build
@@ -25,10 +25,12 @@ configdata_priv.set_quoted('PACKAGE_VERSION', meson.project_version())
 
 configdata_priv.set_quoted('DETERMINATE_NIX_VERSION', fs.read('../../.version-determinate').strip())
 
+subdir('nix-meson-build-support/default-system-cpu')
+
 # Used in public header.
 configdata_pub.set_quoted(
   'NIX_LOCAL_SYSTEM',
-  host_machine.cpu_family() + '-' + host_machine.system(),
+  nix_system_cpu + '-' + host_machine.system(),
   description :
     'This is the system name Nix expects for local running instance of Nix.\n\n'
     + 'See the "system" setting for additional details',
diff --git a/src/libstore/unix/build/darwin-derivation-builder.cc b/src/libstore/unix/build/darwin-derivation-builder.cc
index da8617c34da..d2532512698 100644
--- a/src/libstore/unix/build/darwin-derivation-builder.cc
+++ b/src/libstore/unix/build/darwin-derivation-builder.cc
@@ -160,6 +160,8 @@ struct DarwinDerivationBuilder : DerivationBuilderImpl
 
         if (getEnv("_NIX_TEST_NO_SANDBOX") != "1") {
             Strings sandboxArgs;
+            sandboxArgs.push_back("_NIX_BUILD_TOP");
+            sandboxArgs.push_back(tmpDir);
             sandboxArgs.push_back("_GLOBAL_TMP_DIR");
             sandboxArgs.push_back(globalTmpDir);
             if (drvOptions.allowLocalNetworking) {
diff --git a/src/libstore/unix/build/sandbox-defaults.sb b/src/libstore/unix/build/sandbox-defaults.sb
index 15cd6daf5e0..dd6a064c1bd 100644
--- a/src/libstore/unix/build/sandbox-defaults.sb
+++ b/src/libstore/unix/build/sandbox-defaults.sb
@@ -29,12 +29,14 @@ R""(
 ; Allow getpwuid.
 (allow mach-lookup (global-name "com.apple.system.opendirectoryd.libinfo"))
 
-; Access to /tmp.
+; Access to /tmp and the build directory.
 ; The network-outbound/network-inbound ones are for unix domain sockets, which
 ; we allow access to in TMPDIR (but if we allow them more broadly, you could in
 ; theory escape the sandbox)
 (allow file* process-exec network-outbound network-inbound
-       (literal "/tmp") (subpath TMPDIR))
+       (literal "/tmp")
+       (subpath TMPDIR)
+       (subpath (param "_NIX_BUILD_TOP")))
 
 ; Some packages like to read the system version.
 (allow file-read*
diff --git a/src/nix/main.cc b/src/nix/main.cc
index 256263ad65f..05eddb91fc5 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -213,6 +213,14 @@ struct NixArgs : virtual MultiCommand, virtual MixCommonArgs, virtual RootArgs
    lowdown. */
 static void showHelp(std::vector<std::string> subcommand, NixArgs & toplevel)
 {
+    // Check for aliases if subcommand has exactly one element
+    if (subcommand.size() == 1) {
+        auto alias = toplevel.aliases.find(subcommand[0]);
+        if (alias != toplevel.aliases.end()) {
+            subcommand = alias->second.replacement;
+        }
+    }
+
     auto mdName = subcommand.empty() ? "nix" : fmt("nix3-%s", concatStringsSep("-", subcommand));
 
     evalSettings.restrictEval = false;
diff --git a/tests/functional/meson.build b/tests/functional/meson.build
index cd1bc631978..bd87e9b349d 100644
--- a/tests/functional/meson.build
+++ b/tests/functional/meson.build
@@ -23,6 +23,8 @@ dot = find_program('dot', native : true, required : false)
 
 nix_bin_dir = fs.parent(nix.full_path())
 
+subdir('nix-meson-build-support/default-system-cpu')
+
 test_confdata = {
   'bindir': nix_bin_dir,
   'coreutils': fs.parent(coreutils.full_path()),
@@ -30,7 +32,7 @@ test_confdata = {
   'bash': bash.full_path(),
   'sandbox_shell': busybox.found() ? busybox.full_path() : '',
   'PACKAGE_VERSION': meson.project_version(),
-  'system': host_machine.cpu_family() + '-' + host_machine.system(),
+  'system': nix_system_cpu + '-' + host_machine.system(),
 }
 
 # Just configures `common/vars-and-functions.sh.in`.
diff --git a/tests/functional/misc.sh b/tests/functional/misc.sh
index cb4d4139f4c..b94a5fc578c 100755
--- a/tests/functional/misc.sh
+++ b/tests/functional/misc.sh
@@ -44,3 +44,7 @@ out="$(expectStderr 0 nix-instantiate --option foobar baz --expr '{}')"
 
 out="$(expectStderr 0 nix-instantiate '{}' --option foobar baz --expr )"
 [[ "$(echo "$out" | grep foobar | wc -l)" = 1 ]]
+
+if [[ $(uname) = Linux && $(uname -m) = i686 ]]; then
+    [[ $(nix config show system) = i686-linux ]]
+fi
diff --git a/tests/functional/nix-meson-build-support b/tests/functional/nix-meson-build-support
new file mode 120000
index 00000000000..0b140f56bde
--- /dev/null
+++ b/tests/functional/nix-meson-build-support
@@ -0,0 +1 @@
+../../nix-meson-build-support
\ No newline at end of file
diff --git a/tests/functional/package.nix b/tests/functional/package.nix
index 799026ebe62..36926e0a0be 100644
--- a/tests/functional/package.nix
+++ b/tests/functional/package.nix
@@ -42,6 +42,7 @@ mkMesonDerivation (
 
     workDir = ./.;
     fileset = fileset.unions [
+      ../../nix-meson-build-support
       ../../scripts/nix-profile.sh.in
       ../../.version
       ../../tests/functional