diff --git a/libavcodec/libamr.c b/libavcodec/libamr.c
index 494607f880..79ca57ff37 100644
--- a/libavcodec/libamr.c
+++ b/libavcodec/libamr.c
@@ -245,10 +245,10 @@ static int amr_nb_decode_close(AVCodecContext * avctx)
 
 static int amr_nb_decode_frame(AVCodecContext * avctx,
             void *data, int *data_size,
-            uint8_t * buf, int buf_size)
+            const uint8_t * buf, int buf_size)
 {
     AMRContext *s = avctx->priv_data;
-    uint8_t*amrData=buf;
+    const uint8_t*amrData=buf;
     int offset=0;
     UWord8 toc, q, ft;
     Word16 serial[SERIAL_FRAMESIZE];   /* coded bits */
@@ -441,10 +441,10 @@ static int amr_nb_encode_close(AVCodecContext * avctx)
 
 static int amr_nb_decode_frame(AVCodecContext * avctx,
             void *data, int *data_size,
-            uint8_t * buf, int buf_size)
+            const uint8_t * buf, int buf_size)
 {
     AMRContext *s = avctx->priv_data;
-    uint8_t*amrData=buf;
+    const uint8_t*amrData=buf;
     static const uint8_t block_size[16]={ 12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0 };
     enum Mode dec_mode;
     int packet_size;
@@ -654,10 +654,10 @@ static int amr_wb_decode_init(AVCodecContext * avctx)
 
 static int amr_wb_decode_frame(AVCodecContext * avctx,
             void *data, int *data_size,
-            uint8_t * buf, int buf_size)
+            const uint8_t * buf, int buf_size)
 {
     AMRWBContext *s = avctx->priv_data;
-    uint8_t*amrData=buf;
+    const uint8_t*amrData=buf;
     int mode;
     int packet_size;
     static const uint8_t block_size[16] = {18, 23, 33, 37, 41, 47, 51, 59, 61, 6, 6, 0, 0, 0, 1, 1};