diff --git a/languageassign.module b/languageassign.module
index 238758c..8918d5b 100644
--- a/languageassign.module
+++ b/languageassign.module
@@ -54,15 +54,28 @@ function languageassign_node_operations_callback($nodes, $langcode) {
  * Updates the nody and body languages.
  */
 function languageassign_node_presave($node) {
-  if (property_exists($node, 'languageassign_langcode')) {
-    $newlang = $node->languageassign_langcode;
-    $oldlang = $node->language;
-    // Update node language:
-    $node->language = $newlang;
-    // Update body language:
-    $node->body[$newlang] = $node->body[$oldlang];
-    $node->body[$oldlang] = array();
-    unset($node->languageassign_langcode);
+  if (property_exists($node, 'languageassign_langcode') && field_valid_language($node->languageassign_langcode)) {
+    $new_language = $node->languageassign_langcode;
+    $old_language = $node->language;
+
+    // Update field language when language changed only.
+    if ($old_language != $new_language) {
+      // Update node language:
+      $node->language = $new_language;
+      unset($node->languageassign_langcode);
+
+      // Update field's language:
+      list(,,$bundle) = entity_extract_ids('node', $node);
+      foreach(field_info_instances('node', $bundle) as $instance) {
+        $field_name = $instance['field_name'];
+        $field = field_info_field($field_name);
+
+        if (field_is_translatable('node', $field) && !empty($node->{$field_name})) {
+          $node->{$field_name}[$new_language] = $node->{$field_name}[$old_language];
+          $node->{$field_name}[$old_language] = array();
+        }
+      }
+    }
   }
 }
 
@@ -165,13 +178,28 @@ function languageassign_action_info() {
  * Sets the language field of a node and its body.
  */
 function languageassign_set_node_language_action(&$node, $context) {
-  $oldlang = $node->language;
-  $newlang = $context['language'];
-  // set node language
-  $node->language = $newlang;
-  // set body language
-  $node->body[$newlang] = $node->body[$oldlang];
-  $node->body[$oldlang] = array();
+  if (field_valid_language($context['language'])) {
+    $old_language = $node->language;
+    $new_language = $context['language'];
+
+    // Update field language when language changed only.
+    if ($old_language != $new_language) {
+      // set node language
+      $node->language = $new_language;
+
+      // Update field's language:
+      list(,,$bundle) = entity_extract_ids('node', $node);
+      foreach(field_info_instances('node', $bundle) as $instance) {
+        $field_name = $instance['field_name'];
+        $field = field_info_field($field_name);
+
+        if (field_is_translatable('node', $field) && !empty($node->{$field_name})) {
+          $node->{$field_name}[$new_language] = $node->{$field_name}[$old_language];
+          $node->{$field_name}[$old_language] = array();
+        }
+      }
+    }
+  }
 }
 
 function languageassign_set_node_language_action_form($context) {