diff --git a/ui/build/path.go b/ui/build/path.go
index 7122927..6f5cf78 100644
--- a/ui/build/path.go
+++ b/ui/build/path.go
@@ -55,8 +55,9 @@
 }
 
 // A "lite" version of SetupPath used for dumpvars, or other places that need
-// minimal overhead (but at the expense of logging).
-func SetupLitePath(ctx Context, config Config) {
+// minimal overhead (but at the expense of logging). If tmpDir is empty, the
+// default TMPDIR is used from config.
+func SetupLitePath(ctx Context, config Config, tmpDir string) {
 	if config.pathReplaced {
 		return
 	}
@@ -65,8 +66,11 @@
 	defer ctx.EndTrace()
 
 	origPath, _ := config.Environment().Get("PATH")
-	myPath, _ := config.Environment().Get("TMPDIR")
-	myPath = filepath.Join(myPath, "path")
+
+	if tmpDir == "" {
+		tmpDir, _ = config.Environment().Get("TMPDIR")
+	}
+	myPath := filepath.Join(tmpDir, "path")
 	ensureEmptyDirectoriesExist(ctx, myPath)
 
 	os.Setenv("PATH", origPath)