diff --git a/crates/api/src/site/admin_allow_instance.rs b/crates/api/src/site/admin_allow_instance.rs
index 92de5e22b..ac1b964b0 100644
--- a/crates/api/src/site/admin_allow_instance.rs
+++ b/crates/api/src/site/admin_allow_instance.rs
@@ -22,12 +22,9 @@ pub async fn admin_allow_instance(
 ) -> LemmyResult<Json<SuccessResponse>> {
   is_admin(&local_user_view)?;
 
-  let allowlist = Instance::allowlist(&mut context.pool()).await?;
-  if !allowlist.is_empty() {
-    return Err(
-      LemmyErrorType::Unknown("Using allowlist requires that blocklist be empty".to_string())
-        .into(),
-    );
+  let blocklist = Instance::blocklist(&mut context.pool()).await?;
+  if !blocklist.is_empty() {
+    Err(LemmyErrorType::CannotCombineFederationBlocklistAndAllowlist)?;
   }
 
   let instance_block_form = AdminAllowInstanceForm {
diff --git a/crates/api/src/site/admin_block_instance.rs b/crates/api/src/site/admin_block_instance.rs
index b11bb0c6e..087b7f55e 100644
--- a/crates/api/src/site/admin_block_instance.rs
+++ b/crates/api/src/site/admin_block_instance.rs
@@ -24,10 +24,7 @@ pub async fn admin_block_instance(
 
   let allowlist = Instance::allowlist(&mut context.pool()).await?;
   if !allowlist.is_empty() {
-    return Err(
-      LemmyErrorType::Unknown("Using blocklist requires that allowlist be empty".to_string())
-        .into(),
-    );
+    Err(LemmyErrorType::CannotCombineFederationBlocklistAndAllowlist)?;
   }
 
   let instance_block_form = AdminBlockInstanceForm {
diff --git a/crates/utils/src/error.rs b/crates/utils/src/error.rs
index 906a9006d..40f878747 100644
--- a/crates/utils/src/error.rs
+++ b/crates/utils/src/error.rs
@@ -151,6 +151,7 @@ pub enum LemmyErrorType {
   CommunityHasNoFollowers,
   PostScheduleTimeMustBeInFuture,
   TooManyScheduledPosts,
+  CannotCombineFederationBlocklistAndAllowlist,
   FederationError {
     #[cfg_attr(feature = "full", ts(optional))]
     error: Option<FederationError>,