diff --git a/codec/mjpeg/lex.go b/codec/mjpeg/lex.go
index 46ab4ce8..d8b671b2 100644
--- a/codec/mjpeg/lex.go
+++ b/codec/mjpeg/lex.go
@@ -63,10 +63,7 @@ func Lex(dst io.Writer, src io.Reader, delay time.Duration) error {
 			return nil
 		}
 		if err != nil {
-			if err == io.EOF {
-				return nil
-			}
-			return err
+			return fmt.Errorf("can't read source: %w", err)
 		}
 		if !bytes.Equal(buf, []byte{0xff, 0xd8}) {
 			return fmt.Errorf("parser: not MJPEG frame start: %#v", buf)
@@ -75,10 +72,7 @@ func Lex(dst io.Writer, src io.Reader, delay time.Duration) error {
 		for {
 			b, err := r.ReadByte()
 			if err != nil {
-				if err == io.EOF {
-					return nil
-				}
-				return err
+				return fmt.Errorf("can't read byte: %w", err)
 			}
 			buf = append(buf, b)
 			if last == 0xff && b == 0xd9 {