diff --git a/src/ngx_http_modsecurity_body_filter.c b/src/ngx_http_modsecurity_body_filter.c
index f8b3c71..edf44f6 100644
--- a/src/ngx_http_modsecurity_body_filter.c
+++ b/src/ngx_http_modsecurity_body_filter.c
@@ -150,9 +150,9 @@ ngx_http_modsecurity_body_filter(ngx_http_request_t *r, ngx_chain_t *in)
 
         for (chain = in; chain != NULL; chain = chain->next)
         {
-            u_char *data = chain->buf->start;
+            u_char *data = chain->buf->pos;
 
-            msc_append_response_body(ctx->modsec_transaction, data, chain->buf->end - data);
+            msc_append_response_body(ctx->modsec_transaction, data, chain->buf->last - data);
             ret = ngx_http_modsecurity_process_intervention(ctx->modsec_transaction, r);
             if (ret > 0) {
                 return ngx_http_filter_finalize_request(r,
diff --git a/src/ngx_http_modsecurity_pre_access.c b/src/ngx_http_modsecurity_pre_access.c
index 70f9feb..6f4cbcb 100644
--- a/src/ngx_http_modsecurity_pre_access.c
+++ b/src/ngx_http_modsecurity_pre_access.c
@@ -163,10 +163,10 @@ ngx_http_modsecurity_pre_access_handler(ngx_http_request_t *r)
 
         while (chain && !already_inspected)
         {
-            u_char *data = chain->buf->start;
+            u_char *data = chain->buf->pos;
 
             msc_append_request_body(ctx->modsec_transaction, data,
-                chain->buf->last - chain->buf->pos);
+                chain->buf->last - data);
 
             if (chain->buf->last_buf) {
                 break;