diff --git a/internal/processing/federation/getwebfinger.go b/internal/processing/federation/getwebfinger.go
index 14536549d..cbc4a7ebc 100644
--- a/internal/processing/federation/getwebfinger.go
+++ b/internal/processing/federation/getwebfinger.go
@@ -44,6 +44,9 @@ func (p *processor) GetWebfingerAccount(ctx context.Context, requestedUsername s
 	}
 
 	accountDomain := viper.GetString(config.Keys.AccountDomain)
+	if accountDomain == "" {
+		accountDomain = viper.GetString(config.Keys.Host)
+	}
 
 	// return the webfinger representation
 	return &apimodel.WellKnownResponse{
diff --git a/internal/typeutils/internaltoas.go b/internal/typeutils/internaltoas.go
index b3aaafff0..3adf406cf 100644
--- a/internal/typeutils/internaltoas.go
+++ b/internal/typeutils/internaltoas.go
@@ -623,6 +623,9 @@ func (c *converter) MentionToAS(ctx context.Context, m *gtsmodel.Mention) (vocab
 	var domain string
 	if m.TargetAccount.Domain == "" {
 		accountDomain := viper.GetString(config.Keys.AccountDomain)
+		if accountDomain == "" {
+			accountDomain = viper.GetString(config.Keys.Host)
+		}
 		domain = accountDomain
 	} else {
 		domain = m.TargetAccount.Domain