diff --git a/include/common/buf.h b/include/common/buf.h
index be196f1..488c406 100644
--- a/include/common/buf.h
+++ b/include/common/buf.h
@@ -352,7 +352,7 @@
  *   =0 : not enough data available. <blk*> are left undefined.
  * The buffer is left unaffected. Unused buffers are left in an undefined state.
  */
-static inline size_t b_getblk_nc(struct buffer *buf, char **blk1, int *len1, char **blk2, int *len2, size_t ofs, size_t max)
+static inline size_t b_getblk_nc(const struct buffer *buf, const char **blk1, int *len1, const char **blk2, int *len2, size_t ofs, size_t max)
 {
 	size_t l1;
 
diff --git a/include/proto/channel.h b/include/proto/channel.h
index fdbcc94..eedeaae 100644
--- a/include/proto/channel.h
+++ b/include/proto/channel.h
@@ -53,8 +53,8 @@
 int co_inject(struct channel *chn, const char *msg, int len);
 int co_getline(const struct channel *chn, char *str, int len);
 int co_getblk(const struct channel *chn, char *blk, int len, int offset);
-int co_getline_nc(const struct channel *chn, char **blk1, int *len1, char **blk2, int *len2);
-int co_getblk_nc(const struct channel *chn, char **blk1, int *len1, char **blk2, int *len2);
+int co_getline_nc(const struct channel *chn, const char **blk1, int *len1, const char **blk2, int *len2);
+int co_getblk_nc(const struct channel *chn, const char **blk1, int *len1, const char **blk2, int *len2);
 
 
 /* returns a pointer to the stream the channel belongs to */
diff --git a/src/channel.c b/src/channel.c
index b720024..3b0592f 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -312,7 +312,7 @@
  * The channel status is not changed. The caller must call co_skip() to
  * update it. Unused buffers are left in an undefined state.
  */
-int co_getblk_nc(const struct channel *chn, char **blk1, int *len1, char **blk2, int *len2)
+int co_getblk_nc(const struct channel *chn, const char **blk1, int *len1, const char **blk2, int *len2)
 {
 	if (unlikely(chn->buf->o == 0)) {
 		if (chn->flags & CF_SHUTW)
@@ -333,8 +333,8 @@
  * the '\n'. Unused buffers are left in an undefined state.
  */
 int co_getline_nc(const struct channel *chn,
-                  char **blk1, int *len1,
-                  char **blk2, int *len2)
+                  const char **blk1, int *len1,
+                  const char **blk2, int *len2)
 {
 	int retcode;
 	int l;
diff --git a/src/hlua.c b/src/hlua.c
index 967f05e..eb27ebc 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -1738,9 +1738,9 @@
 	struct appctx *appctx;
 	int len;
 	int nblk;
-	char *blk1;
+	const char *blk1;
 	int len1;
-	char *blk2;
+	const char *blk2;
 	int len2;
 	int skip_at_end = 0;
 	struct channel *oc;
@@ -3633,9 +3633,9 @@
 	struct hlua_appctx *appctx = MAY_LJMP(hlua_checkapplet_tcp(L, 1));
 	struct stream_interface *si = appctx->appctx->owner;
 	int ret;
-	char *blk1;
+	const char *blk1;
 	int len1;
-	char *blk2;
+	const char *blk2;
 	int len2;
 
 	/* Read the maximum amount of data avalaible. */
@@ -3688,9 +3688,9 @@
 	struct stream_interface *si = appctx->appctx->owner;
 	int len = MAY_LJMP(luaL_checkinteger(L, 2));
 	int ret;
-	char *blk1;
+	const char *blk1;
 	int len1;
-	char *blk2;
+	const char *blk2;
 	int len2;
 
 	/* Read the maximum amount of data avalaible. */
@@ -4096,9 +4096,9 @@
 	struct stream_interface *si = appctx->appctx->owner;
 	struct channel *chn = si_ic(si);
 	int ret;
-	char *blk1;
+	const char *blk1;
 	int len1;
-	char *blk2;
+	const char *blk2;
 	int len2;
 
 	/* Maybe we cant send a 100-continue ? */
@@ -4182,9 +4182,9 @@
 	int len = MAY_LJMP(luaL_checkinteger(L, 2));
 	struct channel *chn = si_ic(si);
 	int ret;
-	char *blk1;
+	const char *blk1;
 	int len1;
-	char *blk2;
+	const char *blk2;
 	int len2;
 
 	/* Maybe we cant send a 100-continue ? */
@@ -6626,9 +6626,9 @@
 	struct act_rule *rule = ctx->rule;
 	struct proxy *px = strm->be;
 	struct hlua *hlua = ctx->ctx.hlua_apphttp.hlua;
-	char *blk1;
+	const char *blk1;
 	int len1;
-	char *blk2;
+	const char *blk2;
 	int len2;
 	int ret;
 
diff --git a/src/mux_h2.c b/src/mux_h2.c
index ce39aea..ec5554b 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -2945,7 +2945,7 @@
  * number of bytes sent. The caller must check the stream's status to detect
  * any error which might have happened subsequently to a successful send.
  */
-static size_t h2s_frt_make_resp_headers(struct h2s *h2s, struct buffer *buf, size_t ofs, size_t max)
+static size_t h2s_frt_make_resp_headers(struct h2s *h2s, const struct buffer *buf, size_t ofs, size_t max)
 {
 	struct http_hdr list[MAX_HTTP_HDR];
 	struct h2c *h2c = h2s->h2c;
@@ -3118,7 +3118,7 @@
  * the number of bytes sent. The caller must check the stream's status to
  * detect any error which might have happened subsequently to a successful send.
  */
-static size_t h2s_frt_make_resp_data(struct h2s *h2s, struct buffer *buf, size_t ofs, size_t max)
+static size_t h2s_frt_make_resp_data(struct h2s *h2s, const struct buffer *buf, size_t ofs, size_t max)
 {
 	struct h2c *h2c = h2s->h2c;
 	struct h1m *h1m = &h2s->res;
@@ -3127,7 +3127,7 @@
 	size_t total = 0;
 	int es_now = 0;
 	int size = 0;
-	char *blk1, *blk2;
+	const char *blk1, *blk2;
 	int len1, len2;
 
 	if (h2c_mux_busy(h2c, h2s)) {