diff --git a/manager_test.go b/manager_test.go
index 895164e773e250be8efda21d4afb2a14ccb68560..4ee0ce2a36dd4a9104e2a6cdf43310a0ded5da0d 100644
--- a/manager_test.go
+++ b/manager_test.go
@@ -125,7 +125,7 @@ func TestManager_NewCert(t *testing.T) {
 	if _, err := os.Stat(p); err != nil {
 		t.Fatalf("file not created: %v", err)
 	}
-	p = filepath.Join(m.configDirs[0], "../certs/example.com/private_key.pem")
+	p = filepath.Join(m.configDirs[0], "../certs/example.com/privkey.pem")
 	if _, err := os.Stat(p); err != nil {
 		t.Fatalf("file not created: %v", err)
 	}
diff --git a/storage.go b/storage.go
index 64a938e2bdd45dc7e61e1c7048733382b796af10..cffdf40575281932ecacb1266d1056d03bdffc98 100644
--- a/storage.go
+++ b/storage.go
@@ -25,7 +25,7 @@ type dirStorage struct {
 
 func (d *dirStorage) GetCert(cn string) ([][]byte, crypto.Signer, error) {
 	certPath := filepath.Join(d.root, cn, "fullchain.pem")
-	keyPath := filepath.Join(d.root, cn, "private_key.pem")
+	keyPath := filepath.Join(d.root, cn, "privkey.pem")
 
 	der, err := parseCertsFromFile(certPath)
 	if err != nil {
@@ -53,7 +53,7 @@ func (d *dirStorage) PutCert(cn string, der [][]byte, key crypto.Signer) error {
 
 	for path, data := range filemap {
 		var mode os.FileMode = 0644
-		if strings.HasSuffix(path, "private_key.pem") {
+		if strings.HasSuffix(path, "privkey.pem") {
 			mode = 0400
 		}
 		log.Printf("writing %s (%03o)", path, mode)
@@ -83,7 +83,7 @@ func dumpCertsAndKey(cn string, der [][]byte, key crypto.Signer) (map[string][]b
 	if err != nil {
 		return nil, err
 	}
-	m[filepath.Join(cn, "private_key.pem")] = data
+	m[filepath.Join(cn, "privkey.pem")] = data
 
 	return m, nil
 }