diff --git a/kernel_patches_daemon/patchwork.py b/kernel_patches_daemon/patchwork.py
index 7c89402..c2fd4e1 100644
--- a/kernel_patches_daemon/patchwork.py
+++ b/kernel_patches_daemon/patchwork.py
@@ -751,6 +751,10 @@ async def get_relevant_subjects(self) -> Sequence[Subject]:
             all_series = await asyncio.gather(*tasks)
 
             for series in all_series:
+                if series.subject.strip() == "":
+                    logger.error(f"Malformed series name: {series.name}")
+                    err_malformed_series.add(1)
+                    continue
                 self.known_series[series.id] = series
 
                 if series.subject not in subjects: