diff --git a/main.go b/main.go
index f32c79c..b11e13b 100644
--- a/main.go
+++ b/main.go
@@ -469,6 +469,11 @@ func main() {
 		*s3prefix = *logURL
 	}
 
+	_, err := url.ParseRequestURI(*s3bucket)
+	if err == nil {
+		log.Fatal("scheme provided for s3-bucket, but should not be")
+	}
+
 	cfg, err := config.LoadDefaultConfig(context.Background())
 	if err != nil {
 		log.Fatal(err)