diff --git a/libavformat/mpeg.c b/libavformat/mpeg.c
index db8fc1547a..afa8618a60 100644
--- a/libavformat/mpeg.c
+++ b/libavformat/mpeg.c
@@ -36,7 +36,7 @@
 
 #define MAX_SYNC_SIZE 100000
 
-static int check_pes(uint8_t *p, uint8_t *end){
+static int check_pes(const uint8_t *p, const uint8_t *end){
     int pes1;
     int pes2=      (p[3] & 0xC0) == 0x80
                 && (p[4] & 0xC0) != 0x40