diff --git a/libavcodec/put_bits.h b/libavcodec/put_bits.h
index 132d1331e9..f8046b1d09 100644
--- a/libavcodec/put_bits.h
+++ b/libavcodec/put_bits.h
@@ -142,6 +142,7 @@ static inline void put_bits(PutBitContext *s, int n, unsigned int value)
 #ifdef BITSTREAM_WRITER_LE
     bit_buf |= value << (32 - bit_left);
     if (n >= bit_left) {
+        av_assert2(s->buf_ptr+3<s->buf_end);
         AV_WL32(s->buf_ptr, bit_buf);
         s->buf_ptr+=4;
         bit_buf = (bit_left==32)?0:value >> bit_left;
@@ -155,6 +156,7 @@ static inline void put_bits(PutBitContext *s, int n, unsigned int value)
     } else {
         bit_buf<<=bit_left;
         bit_buf |= value >> (n - bit_left);
+        av_assert2(s->buf_ptr+3<s->buf_end);
         AV_WB32(s->buf_ptr, bit_buf);
         //printf("bitbuf = %08x\n", bit_buf);
         s->buf_ptr+=4;