diff --git a/cmd/restic/cmd_prune.go b/cmd/restic/cmd_prune.go
index c50b3413e..8e3c5b53d 100644
--- a/cmd/restic/cmd_prune.go
+++ b/cmd/restic/cmd_prune.go
@@ -179,6 +179,12 @@ func pruneRepository(gopts GlobalOptions, repo restic.Repository) error {
 	}
 	bar.Done()
 
+	if len(usedBlobs) > stats.blobs {
+		return errors.Fatalf("number of used blobs is larger than number of available blobs!\n" +
+			"Please report this error (along with the output of the 'prune' run) at\n" +
+			"https://github.com/restic/restic/issues/new")
+	}
+
 	Verbosef("found %d of %d data blobs still in use, removing %d blobs\n",
 		len(usedBlobs), stats.blobs, stats.blobs-len(usedBlobs))