diff --git a/libavcodec/mpegvideo_xvmc.c b/libavcodec/mpegvideo_xvmc.c
index b7fedb3bb6..bd0de6935d 100644
--- a/libavcodec/mpegvideo_xvmc.c
+++ b/libavcodec/mpegvideo_xvmc.c
@@ -142,7 +142,7 @@ void ff_xvmc_field_end(MpegEncContext *s)
 
 /**
  * Synthesize the data needed by XvMC to render one macroblock of data.
- * Fill all relevant fields, if necessery do IDCT.
+ * Fill all relevant fields, if necessary do IDCT.
  */
 void ff_xvmc_decode_mb(MpegEncContext *s)
 {