diff --git a/odds/common/store/s3/s3_store.py b/odds/common/store/s3/s3_store.py
index 526ffd6..aa6229d 100644
--- a/odds/common/store/s3/s3_store.py
+++ b/odds/common/store/s3/s3_store.py
@@ -98,6 +98,7 @@ async def getDB(self, resource: Resource, dataset: Dataset) -> str:
                 obj = await bucket.Object(key)
                 await obj.load()
                 # download the file into a temporary file:
+                key = key.replace('/', '_')
                 outfile = self.cachedir / f'{key}.sqlite'
                 if not outfile.exists():
                     await obj.download_file(str(outfile))