diff --git a/tls/generate/generate.go b/tls/generate/generate.go
index 842327dab..1723d7e37 100644
--- a/tls/generate/generate.go
+++ b/tls/generate/generate.go
@@ -71,7 +71,7 @@ func derCert(privKey *rsa.PrivateKey, expiration time.Time, domain string) ([]by
 	}
 
 	if expiration.IsZero() {
-		expiration = time.Now().Add(365)
+		expiration = time.Now().Add(365 * (24 * time.Hour))
 	}
 
 	template := x509.Certificate{