diff --git a/Akku.manifest b/Akku.manifest
index 9c9e459..bb390a7 100644
--- a/Akku.manifest
+++ b/Akku.manifest
@@ -1,7 +1,7 @@
 #!r6rs ; -*- mode: scheme; coding: utf-8 -*-
 (import (akku format manifest))
 
-(akku-package ("scheme-langserver" "1.2.0")
+(akku-package ("scheme-langserver" "1.2.1")
   (synopsis
    "This package is a language server protocol implementation helping scheme programming.")
   (authors "WANG Zheng")
diff --git a/analysis/identifier/rules/library-export.sls b/analysis/identifier/rules/library-export.sls
index 6969ec9..134191b 100644
--- a/analysis/identifier/rules/library-export.sls
+++ b/analysis/identifier/rules/library-export.sls
@@ -49,7 +49,7 @@
   (let* ([ann (index-node-datum/annotations index-node)]
       [expression (annotation-stripped ann)])
     (match expression
-      [('rename (internal-names external-names) **1) 
+      [('rename ((? symbol? internal-names) (? symbol? external-names)) **1) 
         (fold-left
           (lambda (result current-item)
             (let* ([current-children (index-node-children current-item)]
@@ -81,7 +81,7 @@
               `(,@result ,external-index-node)))
           '()
           (cdr (index-node-children index-node)))]
-      [identifier
+      [(? symbol? identifier)
         (let* ([references (find-available-references-for document index-node identifier)]
             [reference-count (length references)])
           (index-node-references-export-to-other-node-set! 
diff --git a/analysis/identifier/rules/library-import.sls b/analysis/identifier/rules/library-import.sls
index 6a21d9a..77f7e5d 100644
--- a/analysis/identifier/rules/library-import.sls
+++ b/analysis/identifier/rules/library-import.sls
@@ -133,7 +133,7 @@
                   (lambda (reference) 
                     (not (equal? current-identifier (identifier-reference-identifier reference))))
                   imported-references)))))]
-      [('except (library-identifier **1) identifier **1) 
+      [('except (library-identifier **1) (? symbol? identifier) **1) 
         (let ([tmp 
               (filter
                 (lambda (reference) 
@@ -177,7 +177,7 @@
                   (lambda (reference) 
                     (not (equal? current-identifier (identifier-reference-identifier reference))))
                   imported-references)))))]
-      [('prefix (library-identifier **1) prefix-id)
+      [('prefix (library-identifier **1) (? symbol? prefix-id))
         (let* ([imported-references (import-references root-library-node library-identifier)]
             [prefixed-references 
               (map 
@@ -194,7 +194,7 @@
                 imported-references)])
           ;;todo: add something to export-to-other-node for current-index-node?
           (append-references-into-ordered-references-for document grand-parent-index-node prefixed-references))]
-      [('rename (library-identifier **1) (external-name internal-name) **1 ) 
+      [('rename (library-identifier **1) ((? symbol? external-name) (? symbol? internal-name)) **1 ) 
         (let loop ([importion-nodes (cddr (index-node-children index-node))]
             [external-names external-name]
             [internal-names internal-name]
@@ -250,7 +250,7 @@
                   (lambda (reference) 
                     (not (equal? current-external-name (identifier-reference-identifier reference))))
                   imported-references)))))]
-      [('alias (library-identifier **1) (external-name internal-name) **1 ) 
+      [('alias (library-identifier **1) ((? symbol? external-name) (? symbol? internal-name)) **1 ) 
         (let loop ([importion-nodes (cddr (index-node-children index-node))]
             [external-names external-name]
             [internal-names internal-name]
@@ -375,7 +375,7 @@
   (let* ([ann (index-node-datum/annotations index-node)]
       [expression (annotation-stripped ann)])
     (match expression
-      [('rename (internal-names external-names) **1) 
+      [('rename ((? symbol? internal-names) (? symbol? external-names)) **1) 
         (let loop ([exportion-nodes (cdr (index-node-children index-node))]
             [result '()])
           (if (null? exportion-nodes)
@@ -383,6 +383,6 @@
             (loop 
               (cdr exportion-nodes)
               (append result (index-node-references-export-to-other-node (cadr (index-node-children (car exportion-nodes))))))))]
-      [identifier (index-node-references-export-to-other-node index-node)]
+      [(? symbol? identifier) (index-node-references-export-to-other-node index-node)]
       [else '()])))
 )
\ No newline at end of file