diff --git a/webform.install b/webform.install
index 6c15c77..e46ca40 100644
--- a/webform.install
+++ b/webform.install
@@ -857,5 +857,11 @@ function webform_update_7321() {
  * Add index on {webform_submitted_data}.data.
  */
 function webform_update_7322() {
+  // MS SQL Server does not support size-limited indexes
+  // and the column type (text) is too big to fit
+  // inside index size limits.
+  if(db_driver() == 'sqlsrv') {
+    return;
+  }
   db_add_index('webform_submitted_data', 'data', array(array('data', 64)));
 }