diff --git a/bench_test.go b/bench_test.go
index ca2df3c..46f2303 100644
--- a/bench_test.go
+++ b/bench_test.go
@@ -29,12 +29,11 @@ func BenchmarkBuild(b *testing.B) {
 	}
 	defer os.RemoveAll(tdir)
 
-	garbleBinaryName := "garble"
+	garbleBin := filepath.Join(tdir, "garble")
 	if runtime.GOOS == "windows" {
-		garbleBinaryName += ".exe"
+		garbleBin += ".exe"
 	}
 
-	garbleBin := filepath.Join(tdir, garbleBinaryName)
 	if err := exec.Command("go", "build", "-o="+garbleBin).Run(); err != nil {
 		b.Fatalf("building garble: %v", err)
 	}