diff --git a/protocol/rtsp/rtsp.go b/protocol/rtsp/rtsp.go
index cd86f154..d88a3206 100644
--- a/protocol/rtsp/rtsp.go
+++ b/protocol/rtsp/rtsp.go
@@ -166,15 +166,15 @@ func ReadResponse(r io.Reader) (*Response, error) {
 		return nil, err
 	}
 
+	if len(s) < minResponse {
+		return nil, errSmallResponse
+	}
+
 	// Check that it was terminated by CRLF.
 	if []byte(s)[len(s)-2] != '\r' {
 		return nil, errors.New("line not terminated by CRLF")
 	}
 
-	if len(s) < minResponse {
-		return nil, errSmallResponse
-	}
-
 	// Split first line.
 	s1 := strings.SplitN(s, " ", 3)