diff --git a/seminar/models.py b/seminar/models.py
index b7147106..63c9bdfa 100644
--- a/seminar/models.py
+++ b/seminar/models.py
@@ -601,7 +601,7 @@ class Cislo(SeminarModelBase):
 		if not self.titulka_nahled or os.path.getmtime(self.titulka_nahled.path) < os.path.getmtime(self.pdf.path):
 			png_filename = pathlib.Path(tempfile.mkdtemp(), 'nahled.png')
 
-			subprocess.call([
+			subprocess.run([
 				"convert",
 				"-density", "300x300",
 				"-geometry", "{}x{}".format(VYSKA, sirka),
@@ -609,7 +609,10 @@ class Cislo(SeminarModelBase):
 				"-flatten",
 				"{}[0]".format(self.pdf.path),  # titulní strana
 				png_filename
-			])
+				],
+				check=True,
+				capture_output=True
+			)
 
 			with open(png_filename,'rb') as f:
 				self.titulka_nahled.save('',f,True)