diff --git a/cmd/keygen/util.go b/cmd/keygen/util.go
index 49f19e5..c16def5 100644
--- a/cmd/keygen/util.go
+++ b/cmd/keygen/util.go
@@ -18,8 +18,8 @@ import (
 )
 
 func getPassphrase() ([]byte, error) {
-	passphrase := os.Getenv("KEY_PASSPHRASE")
-	if passphrase != "" {
+	passphrase, exists := os.LookupEnv("KEY_PASSPHRASE")
+	if exists {
 		return []byte(passphrase), nil
 	}
 	return askPassphrase()