diff --git a/lix/legacy/nix-build.cc b/lix/legacy/nix-build.cc
index f45ce460e..71bf426e1 100644
--- a/lix/legacy/nix-build.cc
+++ b/lix/legacy/nix-build.cc
@@ -190,8 +190,8 @@ static int main_nix_build(AsyncIoRoot & aio, std::string programName, Strings ar
     if (packages && fromArgs)
         throw UsageError("'-p' and '-E' are mutually exclusive");
 
-    AutoDelete tmpDir(createTempDir("", myName));
-    AutoDelete buildTopTmpDir(createTempDir(tmpDir, "build-top"));
+    AutoDelete tmpDir(createTempDir(myName));
+    AutoDelete buildTopTmpDir(createTempSubdir(tmpDir, "build-top"));
     if (outLink.empty())
         outLink = (Path) tmpDir + "/result";
 
diff --git a/lix/libstore/build/local-derivation-goal.cc b/lix/libstore/build/local-derivation-goal.cc
index d6ef42d48..e82e93ebd 100644
--- a/lix/libstore/build/local-derivation-goal.cc
+++ b/lix/libstore/build/local-derivation-goal.cc
@@ -457,7 +457,7 @@ try {
         /* Create a temporary directory where the build will take
            place. */
         tmpDirRoot =
-            createTempDir(buildDir, "nix-build-" + std::string(drvPath.name()), 0700);
+            createTempSubdir(buildDir, "nix-build-" + std::string(drvPath.name()), 0700);
     } catch (SysError & e) {
         /*
          * Fallback to the global tmpdir and create a safe space there
@@ -475,16 +475,14 @@ try {
 #else
         constexpr int toplevelDirMode = 0700;
 #endif
-        auto nixBuildsTmp = createTempDir(
-            "", fmt("nix-builds-%s", geteuid()), toplevelDirMode
-        );
+        auto nixBuildsTmp = createTempDir(fmt("nix-builds-%s", geteuid()), toplevelDirMode);
         printTaggedWarning(
             "Failed to use the system-wide build directory '%s', falling back to a temporary "
             "directory inside '%s'",
             settings.buildDir.get(),
             nixBuildsTmp
         );
-        tmpDirRoot = createTempDir(
+        tmpDirRoot = createTempSubdir(
             nixBuildsTmp, "nix-build-" + std::string(drvPath.name()), 0700
         );
         worker.buildDirOverride = nixBuildsTmp;
diff --git a/lix/libstore/local-store.cc b/lix/libstore/local-store.cc
index 2f0259961..f01b4efa1 100644
--- a/lix/libstore/local-store.cc
+++ b/lix/libstore/local-store.cc
@@ -1415,7 +1415,7 @@ std::pair<Path, AutoCloseFD> LocalStore::createTempDirInStore()
         /* There is a slight possibility that `tmpDir' gets deleted by
            the GC between createTempDir() and when we acquire a lock on it.
            We'll repeat until 'tmpDir' exists and we've locked it. */
-        tmpDirFn = createTempDir(config_.realStoreDir, "tmp");
+        tmpDirFn = createTempSubdir(config_.realStoreDir, "tmp");
         tmpDirFd = sys::open(tmpDirFn, O_RDONLY | O_DIRECTORY);
         if (tmpDirFd.get() < 0) {
             continue;
diff --git a/lix/libstore/ssh.cc b/lix/libstore/ssh.cc
index 09cf01fad..b93b3cff2 100644
--- a/lix/libstore/ssh.cc
+++ b/lix/libstore/ssh.cc
@@ -26,7 +26,7 @@ SSH::SSH(const std::string & host, const std::optional<uint16_t> port, const std
         throw Error("invalid SSH host name '%s'", host);
 
     auto state(state_.lock());
-    state->tmpDir = std::make_unique<AutoDelete>(createTempDir("", "nix", 0700));
+    state->tmpDir = std::make_unique<AutoDelete>(createTempDir("nix", 0700));
 }
 
 void SSH::addCommonSSHOpts(Strings & args)
diff --git a/lix/libstore/temporary-dir.cc b/lix/libstore/temporary-dir.cc
index 5ec97324f..384d064b0 100644
--- a/lix/libstore/temporary-dir.cc
+++ b/lix/libstore/temporary-dir.cc
@@ -6,9 +6,9 @@
 
 namespace nix {
 
-Path createTempDir(const Path & tmpRoot, const Path & prefix, mode_t mode)
+Path createTempDir(const Path & prefix, mode_t mode)
 {
-    return createTempSubdir(tmpRoot.empty() ? defaultTempDir() : tmpRoot, prefix, mode);
+    return createTempSubdir(defaultTempDir(), prefix, mode);
 }
 
 std::pair<AutoCloseFD, Path> createTempFile(const Path & prefix)
diff --git a/lix/libstore/temporary-dir.hh b/lix/libstore/temporary-dir.hh
index 9bc4df9c4..a2a8a0d18 100644
--- a/lix/libstore/temporary-dir.hh
+++ b/lix/libstore/temporary-dir.hh
@@ -8,7 +8,7 @@ namespace nix {
 /**
  * Create a temporary directory.
  */
-Path createTempDir(const Path & tmpRoot = "", const Path & prefix = "nix", mode_t mode = 0755);
+Path createTempDir(const Path & prefix = "nix", mode_t mode = 0755);
 
 /**
  * Create a temporary file, returning a file handle and its path.
diff --git a/lix/nix/develop.cc b/lix/nix/develop.cc
index eb81529b8..202d5fdbb 100644
--- a/lix/nix/develop.cc
+++ b/lix/nix/develop.cc
@@ -574,7 +574,7 @@ struct CmdDevelop : Common, MixEnvironment
 
         auto [rcFileFd, rcFilePath] = createTempFile("nix-shell");
 
-        AutoDelete tmpDir(createTempDir("", "nix-develop"), true);
+        AutoDelete tmpDir(createTempDir("nix-develop"), true);
 
         auto script = makeRcScript(*state, store, buildEnvironment, (Path) tmpDir);
 
@@ -714,7 +714,7 @@ struct CmdPrintDevEnv : Common, MixJSON
         if (json) {
             logger->writeToStdout(buildEnvironment.toJSON());
         } else {
-            AutoDelete tmpDir(createTempDir("", "nix-dev-env"), true);
+            AutoDelete tmpDir(createTempDir("nix-dev-env"), true);
             logger->writeToStdout(makeRcScript(*state, store, buildEnvironment, tmpDir));
         }
     }