diff --git a/seminar/models.py b/seminar/models.py
index 7855b040..8fed002c 100644
--- a/seminar/models.py
+++ b/seminar/models.py
@@ -608,7 +608,7 @@ class Cislo(SeminarModelBase):
 				"-dNOPAUSE",
 				"-dBATCH",
 				"-dNOPROMPT",
-				"-sDEVICE=pngalpha",
+				"-sDEVICE=png16m",
 				"-r{}x{}".format(VYSKA, sirka),
 				"-dFirstPage=1d",
 				"-dLastPage=1d",