diff --git a/include/proto/spoe.h b/include/proto/spoe.h
index e5b3b4b..86328ad 100644
--- a/include/proto/spoe.h
+++ b/include/proto/spoe.h
@@ -121,7 +121,7 @@
  * many bytes has been encoded. If <*off> is zero at the end, it means that all
  * data has been encoded. */
 static inline int
-spoe_encode_data(struct sample *smp, unsigned int *off, char **buf, char *end)
+spoe_encode_data(unsigned int *len, struct sample *smp, unsigned int *off, char **buf, char *end)
 {
 	char *p = *buf;
 	int   ret;
@@ -185,15 +185,16 @@
 							      end);
 				if (ret == -1)
 					return -1;
+				*len = chk->data;
 			}
 			else {
 				/* The sample has been fragmented, encode remaining data */
-				ret = MIN(chk->data - *off, end - p);
+				ret = MIN(*len - *off, end - p);
 				memcpy(p, chk->area + *off, ret);
 				p += ret;
 			}
 			/* Now update <*off> */
-			if (ret + *off != chk->data)
+			if (ret + *off != *len)
 				*off += ret;
 			else
 				*off = 0;
diff --git a/include/types/spoe.h b/include/types/spoe.h
index a744cd7..9bba492 100644
--- a/include/types/spoe.h
+++ b/include/types/spoe.h
@@ -323,6 +323,7 @@
 		struct spoe_message *curmsg;      /* SPOE message from which to resume encoding */
 		struct spoe_arg     *curarg;      /* SPOE arg in <curmsg> from which to resume encoding */
 		unsigned int         curoff;      /* offset in <curarg> from which to resume encoding */
+		unsigned int         curlen;      /* length of <curarg> need to be encode, for SMP_F_MAY_CHANGE data */
 		unsigned int         flags;       /* SPOE_FRM_FL_* */
 	} frag_ctx; /* Info about fragmented frames, valid on if SPOE_CTX_FL_FRAGMENTED is set */