diff --git a/plugins/talks.py b/plugins/talks.py
index 387c0e0..8d881f5 100644
--- a/plugins/talks.py
+++ b/plugins/talks.py
@@ -182,7 +182,7 @@ class TalkGridDirective(Directive):
             rooms = tuple(sorted(unique_attr(talks, 'room')))
             mintime = min({talk['time'].hour * 60 +
                            talk['time'].minute
-                           for talk in talks}) / GRID_STEP * GRID_STEP
+                           for talk in talks}) // GRID_STEP * GRID_STEP
             maxtime = max({talk['time'].hour * 60 +
                            talk['time'].minute +
                            talk['duration']
@@ -197,7 +197,7 @@ class TalkGridDirective(Directive):
                 assert position in times
                 roomnum = rooms.index(talk['room'])
                 times[position][roomnum] = talk
-                for i in range(1, talk['duration'] / GRID_STEP):
+                for i in range(1, talk['duration'] // GRID_STEP):
                     times[position + i*GRID_STEP][roomnum] = 'skip'
 
             render = tmpl.render(times=times,