diff --git a/lib/fugit/cron.rb b/lib/fugit/cron.rb
index 952201d..abcae6a 100644
--- a/lib/fugit/cron.rb
+++ b/lib/fugit/cron.rb
@@ -485,6 +485,8 @@ def expand(min, max, r)
 
       sla = nil if sla == 1 # don't get fooled by /1
 
+      edn = max if sla && edn.nil?
+
       return [ nil ] if sta.nil? && edn.nil? && sla.nil?
       return [ sta ] if sta && edn.nil?
 
diff --git a/spec/cron_spec.rb b/spec/cron_spec.rb
index 1d065b0..fbd66c3 100644
--- a/spec/cron_spec.rb
+++ b/spec/cron_spec.rb
@@ -117,6 +117,10 @@
     [ '59 18 * * 2#2', '2021-02-09 18:59:00', '2021-02-09 17:41:10' ],
     [ '59 18 * * 2#2', '2021-02-09 18:59:00', '2021-02-09 17:41:10', 'UTC' ],
     #[ '59 18 * * 2#1', '2021-02-09 18:59:00', '2021-02-09 17:41:10', 'utc' ],
+
+    [ '15/30 * * * *', '2021-02-09 19:15:00', '2021-02-09 19:00:00' ],
+    [ '15/30 * * * *', '2021-02-09 19:45:00', '2021-02-09 19:30:00' ],
+    [ '15-40/30 * * * *', '2021-02-09 20:15:00', '2021-02-09 19:30:00' ],
   ]
 
   describe '#next_time' do