diff --git a/unmount_linux.go b/unmount_linux.go
index 6a165cc..86abc8d 100644
--- a/unmount_linux.go
+++ b/unmount_linux.go
@@ -2,20 +2,22 @@ package fuseshim
 
 import (
 	"bytes"
-	"errors"
+	"fmt"
 	"os/exec"
 )
 
-func unmount(dir string) error {
+func unmount(dir string) (err error) {
+	// Call fusermount.
 	cmd := exec.Command("fusermount", "-u", dir)
 	output, err := cmd.CombinedOutput()
 	if err != nil {
 		if len(output) > 0 {
 			output = bytes.TrimRight(output, "\n")
-			msg := err.Error() + ": " + string(output)
-			err = errors.New(msg)
+			err = fmt.Errorf("%v: %s", err, output)
 		}
-		return err
+
+		return
 	}
-	return nil
+
+	return
 }