diff --git a/src/http/ngx_http_cache.h b/src/http/ngx_http_cache.h
index cd0b4bb..d010a4e 100644
--- a/src/http/ngx_http_cache.h
+++ b/src/http/ngx_http_cache.h
@@ -80,6 +80,7 @@
     ngx_str_t                        vary;
     u_char                           variant[NGX_HTTP_CACHE_KEY_LEN];
 
+    size_t                           buffer_size;
     size_t                           header_start;
     size_t                           body_start;
     off_t                            length;
diff --git a/src/http/ngx_http_file_cache.c b/src/http/ngx_http_file_cache.c
index e985f27..7a5b4ca 100644
--- a/src/http/ngx_http_file_cache.c
+++ b/src/http/ngx_http_file_cache.c
@@ -294,6 +294,8 @@
         cln->data = c;
     }
 
+    c->buffer_size = c->body_start;
+
     rc = ngx_http_file_cache_exists(cache, c);
 
     ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
@@ -1230,7 +1232,7 @@
 
     c->secondary = 1;
     c->file.name.len = 0;
-    c->body_start = c->buf->end - c->buf->start;
+    c->body_start = c->buffer_size;
 
     ngx_memcpy(c->key, c->variant, NGX_HTTP_CACHE_KEY_LEN);