diff --git a/app/controllers/account/join_codes_controller.rb b/app/controllers/account/join_codes_controller.rb
index fba2ccfe9..217ee603c 100644
--- a/app/controllers/account/join_codes_controller.rb
+++ b/app/controllers/account/join_codes_controller.rb
@@ -9,8 +9,11 @@ class Account::JoinCodesController < ApplicationController
   end
 
   def update
-    @join_code.update!(join_code_params)
-    redirect_to account_join_code_path
+    if @join_code.update(join_code_params)
+      redirect_to account_join_code_path
+    else
+      render :edit, status: :unprocessable_entity
+    end
   end
 
   def destroy
diff --git a/app/models/account/join_code.rb b/app/models/account/join_code.rb
index 82283e4f6..79160cbaa 100644
--- a/app/models/account/join_code.rb
+++ b/app/models/account/join_code.rb
@@ -1,8 +1,11 @@
 class Account::JoinCode < ApplicationRecord
   CODE_LENGTH = 12
+  USAGE_LIMIT_MAX = 10_000_000_000
 
   belongs_to :account
 
+  validates :usage_limit, numericality: { less_than_or_equal_to: USAGE_LIMIT_MAX, message: "cannot be larger than the population of the planet" }
+
   scope :active, -> { where("usage_count < usage_limit") }
 
   before_create :generate_code, if: -> { code.blank? }
diff --git a/app/views/account/join_codes/edit.html.erb b/app/views/account/join_codes/edit.html.erb
index bca92e58f..8a65adca7 100644
--- a/app/views/account/join_codes/edit.html.erb
+++ b/app/views/account/join_codes/edit.html.erb
@@ -14,12 +14,21 @@
 
   <%= form_with model: @join_code, url: account_join_code_path, method: :patch, data: { controller: "form" }, html: { class: "flex flex-column gap" } do |form| %>
     <%= form.number_field :usage_limit,
-          required: true, autofocus: true, min: @join_code.usage_count,
+          required: true, autofocus: true,
+          in: 0..Account::JoinCode::USAGE_LIMIT_MAX,
           class: "input center txt-large fit-content font-weight-black txt-align-center", style: "max-inline-size: 8ch",
           data: { action: "keydown.esc@document->form#cancel focus->form#select" } %>
 
+    <% if @join_code.errors.any? %>
+      <div class="txt-negative txt-small">
+        <% @join_code.errors.full_messages.each do |message| %>
+          <p class="margin-block-none"><%= message %></p>
+        <% end %>
+      </div>
+    <% end %>
+
     <p class="margin-none txt-subtle">
-      This code has been used <%= @join_code.usage_count %>/<%= @join_code.usage_limit %> times.
+      This code has been used <%= @join_code.usage_count %>/<%= @join_code.usage_limit_in_database %> times.
     </p>
 
     <%= form.button type: :submit, class: "btn btn--link center txt-medium", data: { form_target: "submit" } do %>
diff --git a/test/controllers/accounts/join_codes_controller_test.rb b/test/controllers/accounts/join_codes_controller_test.rb
index 33c118386..15d41b5ec 100644
--- a/test/controllers/accounts/join_codes_controller_test.rb
+++ b/test/controllers/accounts/join_codes_controller_test.rb
@@ -37,4 +37,14 @@ class Account::JoinCodesControllerTest < ActionDispatch::IntegrationTest
     delete account_join_code_path
     assert_response :forbidden
   end
+
+  test "update with extremely large usage_limit" do
+    # A number larger than bigint max (2^63 - 1 = 9223372036854775807)
+    huge_number = "99999999999999999999999999999999999"
+
+    put account_join_code_path, params: { account_join_code: { usage_limit: huge_number } }
+
+    assert_response :unprocessable_entity
+    assert_select ".txt-negative", text: /cannot be larger than the population of the planet/
+  end
 end