diff --git a/lib/promscrape/client.go b/lib/promscrape/client.go
index 333c5a2ec0..835c08e050 100644
--- a/lib/promscrape/client.go
+++ b/lib/promscrape/client.go
@@ -324,7 +324,7 @@ func (c *client) ReadData(dst []byte) ([]byte, error) {
 	if len(dst) > c.hc.MaxResponseBodySize {
 		maxScrapeSizeExceeded.Inc()
 		return dst, fmt.Errorf("the response from %q exceeds -promscrape.maxScrapeSize=%d (the actual response size is %d bytes); "+
-			"either reduce the response size for the target or increase -promscrape.maxScrapeSize", c.scrapeURL, len(dst), maxScrapeSize.N)
+			"either reduce the response size for the target or increase -promscrape.maxScrapeSize", c.scrapeURL, maxScrapeSize.N, len(dst))
 	}
 	if statusCode != fasthttp.StatusOK {
 		metrics.GetOrCreateCounter(fmt.Sprintf(`vm_promscrape_scrapes_total{status_code="%d"}`, statusCode)).Inc()