diff --git a/codec/h264/lex.go b/codec/h264/lex.go
index 633d3f53..6159a15e 100644
--- a/codec/h264/lex.go
+++ b/codec/h264/lex.go
@@ -72,7 +72,13 @@ func Lex(dst io.Writer, src io.Reader, delay time.Duration) error {
 		var err error
 		buf, b, err = c.ScanUntil(buf, 0x00)
 		if err != nil {
-			return err
+			if err != io.EOF {
+				return err
+			}
+			if len(buf) != 0 {
+				return io.ErrUnexpectedEOF
+			}
+			return io.EOF
 		}
 
 		for n := 1; b == 0x0 && n < 4; n++ {