diff --git a/unwind/imdb_import.py b/unwind/imdb_import.py
index bccb18a..705db2f 100644
--- a/unwind/imdb_import.py
+++ b/unwind/imdb_import.py
@@ -198,7 +198,9 @@ async def import_from_file(*, basics_path: Path, ratings_path: Path):
 
     log.info("💾 Importing movies ...")
     total = count_lines(basics_path)
-    assert total != 0
+    log.debug("Found %i movies.", total)
+    if total == 0:
+        raise RuntimeError(f"No movies found.")
     perc_next_report = 0.0
     perc_step = 0.1