diff --git a/lib/puma/dsl.rb b/lib/puma/dsl.rb
index ddf26f7737..0d81c94fe4 100644
--- a/lib/puma/dsl.rb
+++ b/lib/puma/dsl.rb
@@ -46,10 +46,10 @@ def self.ssl_bind_str(host, port, opts)
         else ''
         end
 
-      backlog_str = opts[:backlog] ? "&backlog=#{opts[:backlog]}" : ''
-
       ca_additions = "&ca=#{opts[:ca]}" if ['peer', 'force_peer'].include?(verify)
 
+      backlog_str = opts[:backlog] ? "&backlog=#{Integer(opts[:backlog])}" : ''
+
       if defined?(JRUBY_VERSION)
         ssl_cipher_list = opts[:ssl_cipher_list] ?
           "&ssl_cipher_list=#{opts[:ssl_cipher_list]}" : nil