diff --git a/sources/org.osbuild.ostree b/sources/org.osbuild.ostree
index fddb914a..60950150 100755
--- a/sources/org.osbuild.ostree
+++ b/sources/org.osbuild.ostree
@@ -11,6 +11,7 @@ import os
 import sys
 import subprocess
 import uuid
+from osbuild.util.ostree import show
 
 from osbuild import sources
 
@@ -122,8 +123,12 @@ class OSTreeSource(sources.SourceService):
         ostree("config", "set", "repo.locking", "true", repo=self.repo)
 
     # pylint: disable=[no-self-use]
-    def exists(self, _checksum, _item):
-        return False
+    def exists(self, checksum, _desc):
+        try:
+            show(self.repo, checksum)
+        except RuntimeError:
+            return False
+        return True
 
 
 def main():