diff --git a/cred/md5-user-salt.go b/cred/md5-user-salt.go
index 6a83e414..429f644e 100644
--- a/cred/md5-user-salt.go
+++ b/cred/md5-user-salt.go
@@ -41,9 +41,17 @@ func (cm *Md5UserSaltCredManager) GetHashedPassword(password string, salt string
 	if salt == "" {
 		return getMd5HexDigest(password)
 	}
+
 	return getMd5HexDigest(getMd5HexDigest(password) + salt)
 }
 
 func (cm *Md5UserSaltCredManager) IsPasswordCorrect(plainPwd string, hashedPwd string, salt string) bool {
+	// For backward-compatibility
+	if salt == "" {
+		if hashedPwd == cm.GetHashedPassword(getMd5HexDigest(plainPwd), salt) {
+			return true
+		}
+	}
+
 	return hashedPwd == cm.GetHashedPassword(plainPwd, salt)
 }
diff --git a/cred/sha256-salt.go b/cred/sha256-salt.go
index acd44e29..aa7a4ff6 100644
--- a/cred/sha256-salt.go
+++ b/cred/sha256-salt.go
@@ -41,9 +41,17 @@ func (cm *Sha256SaltCredManager) GetHashedPassword(password string, salt string)
 	if salt == "" {
 		return getSha256HexDigest(password)
 	}
+
 	return getSha256HexDigest(getSha256HexDigest(password) + salt)
 }
 
 func (cm *Sha256SaltCredManager) IsPasswordCorrect(plainPwd string, hashedPwd string, salt string) bool {
+	// For backward-compatibility
+	if salt == "" {
+		if hashedPwd == cm.GetHashedPassword(getSha256HexDigest(plainPwd), salt) {
+			return true
+		}
+	}
+
 	return hashedPwd == cm.GetHashedPassword(plainPwd, salt)
 }
diff --git a/cred/sha512-salt.go b/cred/sha512-salt.go
index c3bee357..606c5f57 100644
--- a/cred/sha512-salt.go
+++ b/cred/sha512-salt.go
@@ -41,9 +41,17 @@ func (cm *Sha512SaltCredManager) GetHashedPassword(password string, salt string)
 	if salt == "" {
 		return getSha512HexDigest(password)
 	}
+
 	return getSha512HexDigest(getSha512HexDigest(password) + salt)
 }
 
 func (cm *Sha512SaltCredManager) IsPasswordCorrect(plainPwd string, hashedPwd string, salt string) bool {
+	// For backward-compatibility
+	if salt == "" {
+		if hashedPwd == cm.GetHashedPassword(getSha512HexDigest(plainPwd), salt) {
+			return true
+		}
+	}
+
 	return hashedPwd == cm.GetHashedPassword(plainPwd, salt)
 }