diff --git a/app/index.rb b/app/index.rb
index 5da91a23..f2c52de9 100644
--- a/app/index.rb
+++ b/app/index.rb
@@ -148,7 +148,11 @@ post '/forgot_username' do
     redirect '/forgot_username'
   end
 
-  sites = Site.get_recovery_sites_with_email params[:email]
+  begin
+    sites = Site.get_recovery_sites_with_email params[:email]
+  rescue ArgumentError
+    redirect '/forgot_username'
+  end
 
   sites.each do |site|
     body = <<-EOT