diff --git a/src/http/modules/ngx_http_ssi_filter_module.c b/src/http/modules/ngx_http_ssi_filter_module.c
index b02300f..0d86e69 100644
--- a/src/http/modules/ngx_http_ssi_filter_module.c
+++ b/src/http/modules/ngx_http_ssi_filter_module.c
@@ -1204,7 +1204,7 @@
 
                 if (ctx->value_buf == NULL) {
                     ctx->param->value.data = ngx_pnalloc(r->pool,
-                                                         ctx->value_len);
+                                                         ctx->value_len + 1);
                     if (ctx->param->value.data == NULL) {
                         return NGX_ERROR;
                     }
@@ -1375,6 +1375,16 @@
         case ssi_quoted_symbol_state:
             state = ctx->saved_state;
 
+            if (ctx->param->value.len == ctx->value_len) {
+                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+                              "too long \"%V%c...\" value of \"%V\" "
+                              "parameter in \"%V\" SSI command",
+                              &ctx->param->value, ch, &ctx->param->key,
+                              &ctx->command);
+                state = ssi_error_state;
+                break;
+            }
+
             ctx->param->value.data[ctx->param->value.len++] = ch;
 
             break;
@@ -2886,7 +2896,7 @@
                          prev->ignore_recycled_buffers, 0);
 
     ngx_conf_merge_size_value(conf->min_file_chunk, prev->min_file_chunk, 1024);
-    ngx_conf_merge_size_value(conf->value_len, prev->value_len, 256);
+    ngx_conf_merge_size_value(conf->value_len, prev->value_len, 255);
 
     if (ngx_http_merge_types(cf, &conf->types_keys, &conf->types,
                              &prev->types_keys, &prev->types,