diff --git a/trytond/report/report.py b/trytond/report/report.py
index 0ef40ccb99..36db0661e8 100644
--- a/trytond/report/report.py
+++ b/trytond/report/report.py
@@ -342,7 +342,7 @@ class Report(URLMixin, PoolBase):
                 and output_format == 'pdf'):
             return output_format, weasyprint.HTML(string=data).write_pdf()
 
-        if output_format in MIMETYPES:
+        if input_format == output_format and output_format in MIMETYPES:
             return output_format, data
 
         dtemp = tempfile.mkdtemp(prefix='trytond_')