diff --git a/src/pretix/base/pdf.py b/src/pretix/base/pdf.py
index 1f01ce9965..791d8735c2 100644
--- a/src/pretix/base/pdf.py
+++ b/src/pretix/base/pdf.py
@@ -194,7 +194,7 @@ class Renderer:
         self.background_file = background_file
         self.variables = get_variables(event)
         if self.background_file:
-            self.bg_pdf = PdfFileReader(BytesIO(self.background_file.read()))
+            self.bg_pdf = PdfFileReader(BytesIO(self.background_file.read()), strict=False)
         else:
             self.bg_pdf = None