diff --git a/libavcodec/bitstream.c b/libavcodec/bitstream.c
index 5c50120460..b74775e9c0 100644
--- a/libavcodec/bitstream.c
+++ b/libavcodec/bitstream.c
@@ -50,7 +50,7 @@ void align_put_bits(PutBitContext *s)
 #endif
 }
 
-void ff_put_string(PutBitContext * pbc, char *s, int put_zero)
+void ff_put_string(PutBitContext * pbc, const char *s, int put_zero)
 {
     while(*s){
         put_bits(pbc, 8, *s);
@@ -60,9 +60,9 @@ void ff_put_string(PutBitContext * pbc, char *s, int put_zero)
         put_bits(pbc, 8, 0);
 }
 
-void ff_copy_bits(PutBitContext *pb, uint8_t *src, int length)
+void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length)
 {
-    const uint16_t *srcw= (uint16_t*)src;
+    const uint16_t *srcw= (const uint16_t*)src;
     int words= length>>4;
     int bits= length&15;
     int i;
diff --git a/libavcodec/bitstream.h b/libavcodec/bitstream.h
index 854ba99bcc..0a6f7de53e 100644
--- a/libavcodec/bitstream.h
+++ b/libavcodec/bitstream.h
@@ -137,8 +137,8 @@ static inline void flush_put_bits(PutBitContext *s)
 }
 
 void align_put_bits(PutBitContext *s);
-void ff_put_string(PutBitContext * pbc, char *s, int put_zero);
-void ff_copy_bits(PutBitContext *pb, uint8_t *src, int length);
+void ff_put_string(PutBitContext * pbc, const char *s, int put_zero);
+void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
 
 /* bit input */
 /* buffer, buffer_end and size_in_bits must be present and used by every reader */