diff --git a/main.go b/main.go
index ac88fc1..90d2d56 100644
--- a/main.go
+++ b/main.go
@@ -876,7 +876,7 @@ func validateSource(source string) error {
 		return nil
 	}
 
-	r, err := regexp.Compile(`^oci:|dir:|file:`)
+	r, err := regexp.Compile(`^oci:|^dir:|^file:`)
 	if err != nil {
 		return err
 	}