diff --git a/src/codec/encoder/subtitle.rs b/src/codec/encoder/subtitle.rs
index 4e8bc22..64b40b6 100644
--- a/src/codec/encoder/subtitle.rs
+++ b/src/codec/encoder/subtitle.rs
@@ -1,4 +1,4 @@
-use std::ops::Deref;
+use std::ops::{Deref, DerefMut};
 
 use libc::c_int;
 use ffi::*;
@@ -26,3 +26,9 @@ impl Deref for Subtitle {
 		&self.0
 	}
 }
+
+impl DerefMut for Subtitle {
+	fn deref_mut(&mut self) -> &mut<Self as Deref>::Target {
+		&mut self.0
+	}
+}