diff --git a/main.go b/main.go
index 2ab4680..1631f4a 100644
--- a/main.go
+++ b/main.go
@@ -10,12 +10,12 @@ import (
 	"os"
 	"os/exec"
 	"strings"
-	"syscall"
 
 	"github.com/alecthomas/chroma"
 	"github.com/alecthomas/chroma/formatters/html"
 	"github.com/alecthomas/chroma/lexers"
 	"github.com/alecthomas/chroma/styles"
+	"golang.org/x/sys/unix"
 )
 
 // dataPipedIn returns true if the user piped data via stdin.
@@ -132,7 +132,6 @@ func main() {
 		}
 	}
 	checkError(bs.Err(), "reading markdown file")
-	_ = needCSS
 	f, err := ioutil.TempFile("", "chroma-markdown-")
 	checkError(err, "creating temporary file")
 	w := bufio.NewWriter(f)
@@ -149,6 +148,9 @@ func main() {
 		cmark, lookErr = exec.LookPath("markdown")
 		checkError(lookErr, "finding markdown binary")
 	}
-	execErr := syscall.Exec(cmark, []string{cmark, f.Name()}, []string{})
+	execErr := unix.Exec(cmark, []string{cmark, f.Name()}, []string{})
 	checkError(execErr, "executing markdown binary")
+	if err := f.Close(); err != nil {
+		checkError(err, "closing file")
+	}
 }