diff --git a/graphviz_dot_hooks/check_dot.py b/graphviz_dot_hooks/check_dot.py
index b53c585..0ea45a7 100644
--- a/graphviz_dot_hooks/check_dot.py
+++ b/graphviz_dot_hooks/check_dot.py
@@ -10,11 +10,12 @@
 def _verify_dot_rendering(dot_filepath: str) -> Tuple[bool, Optional[str]]:
     """Trying to render it would detect syntax error, there are probably cheaper way to check this
     but we aren't really looking after performance here"""
+    format = "svg"
     with tempfile.NamedTemporaryFile(suffix=f".{format}") as tmpf:
         try:
             # arbitrary render as svg (more generic than png)
             # but it doesn't matter much as we are mostly interested in .dot syntax
-            render("dot", "svg", dot_filepath, outfile=tmpf.name)
+            render("dot", format, dot_filepath, outfile=tmpf.name)
         except CalledProcessError as ex:
             return False, str(ex)