diff --git a/storage/filesystem.go b/storage/filesystem.go
index 04e383d..ce9f00b 100644
--- a/storage/filesystem.go
+++ b/storage/filesystem.go
@@ -425,7 +425,8 @@ func (b *filesystemBackend) PutAddressObject(ctx context.Context, objPath string
 		return "", err
 	}
 
-	if _, err := os.Stat(localPath); !os.IsNotExist(err) {
+	// TODO handle IfMatch
+	if _, err := os.Stat(localPath); !os.IsNotExist(err) && opts.IfNoneMatch {
 		return "", carddav.NewPreconditionError(carddav.PreconditionNoUIDConflict)
 	}
 
@@ -603,7 +604,8 @@ func (b *filesystemBackend) PutCalendarObject(ctx context.Context, objPath strin
 		return "", err
 	}
 
-	if _, err := os.Stat(localPath); !os.IsNotExist(err) {
+	// TODO handle IfMatch
+	if _, err := os.Stat(localPath); !os.IsNotExist(err) && opts.IfNoneMatch {
 		return "", caldav.NewPreconditionError(caldav.PreconditionNoUIDConflict)
 	}