diff --git a/ingestify/__init__.py b/ingestify/__init__.py
index 23ca0ca..c3f5b44 100644
--- a/ingestify/__init__.py
+++ b/ingestify/__init__.py
@@ -9,4 +9,4 @@
     from .source_base import Source, DatasetResource
     from .main import debug_source
 
-__version__ = "0.12.0"
+__version__ = "0.12.1"
diff --git a/ingestify/infra/event_log/consumer.py b/ingestify/infra/event_log/consumer.py
index a75851a..696c6b7 100644
--- a/ingestify/infra/event_log/consumer.py
+++ b/ingestify/infra/event_log/consumer.py
@@ -77,8 +77,8 @@ def _update_cursor(self, conn, event_id: int) -> None:
         )
         conn.commit()
 
-    def _run_once(self, on_event: Callable, batch_size: int = 100) -> bool:
-        """Returns True on success, False if a processing error occurred."""
+    def _run_once(self, on_event: Callable, batch_size: int = 100) -> int:
+        """Returns number of events processed, or -1 if a processing error occurred."""
         with self._engine.connect() as conn:
             self._ensure_reader_state(conn)
             last_id = self._get_last_event_id(conn)
@@ -95,10 +95,10 @@ def _run_once(self, on_event: Callable, batch_size: int = 100) -> bool:
                         event_id,
                         type(event).event_type,
                     )
-                    return False
+                    return -1
                 self._update_cursor(conn, event_id)
 
-        return True
+        return len(rows)
 
     def run(
         self,
@@ -107,7 +107,10 @@ def run(
         batch_size: int = 100,
     ) -> int:
         while True:
-            success = self._run_once(on_event, batch_size)
-            if not success or poll_interval is None:
-                return 0 if success else 1
-            time.sleep(poll_interval)
+            count = self._run_once(on_event, batch_size)
+            if count < 0:
+                return 1
+            if count == 0:
+                if poll_interval is None:
+                    return 0
+                time.sleep(poll_interval)
diff --git a/ingestify/tests/test_event_log.py b/ingestify/tests/test_event_log.py
index db8d3c5..9d0d15c 100644
--- a/ingestify/tests/test_event_log.py
+++ b/ingestify/tests/test_event_log.py
@@ -80,7 +80,7 @@ def test_consumer_processes_events(consumer, dataset):
 
 def test_consumer_cursor_not_advanced_on_error(consumer, dataset):
     consumer._event_log.write(RevisionAdded(dataset=dataset))
-    assert not consumer._run_once(lambda e: 1 / 0)
+    assert consumer._run_once(lambda e: 1 / 0) == -1
     # Next run still sees the same event
     received = []
     consumer._run_once(lambda e: received.append(e))