diff --git a/formula_field.install b/formula_field.install
index a89cbd1..f836bf6 100644
--- a/formula_field.install
+++ b/formula_field.install
@@ -14,3 +14,28 @@ function formula_field_field_schema($field) {
     ),
   );
 }
+
+/**
+ * Implementation of hook_requirements().
+ */
+function formula_field_requirements($phase) {
+  $requirements = array();
+  $t = get_t();
+
+  $requirements['eval-math-master'] = array(
+    'title' => $t('eval-math-master Library'),
+  );
+
+  $libraries = libraries_get_libraries();
+  if (isset($libraries['eval-math-master'])) {
+    $requirements['eval-math-master']['value'] = $t('Installed');
+    $requirements['eval-math-master']['severity'] = REQUIREMENT_OK;
+  }
+  else {
+    $requirements['eval-math-master']['value'] = $t('Not Installed');
+    $requirements['eval-math-master']['severity'] = REQUIREMENT_ERROR;
+    $requirements['eval-math-master']['description'] = $t('The eval-math-master library is missing. Please install library from ').'<a href=https://github.com/dbojdo/eval-math>'. $t('here').'</a>';
+  }
+
+  return $requirements;
+}
diff --git a/formula_field.module b/formula_field.module
index a5098ea..493ccb2 100644
--- a/formula_field.module
+++ b/formula_field.module
@@ -1,9 +1,10 @@
 <?php
 
+use Webit\Util\EvalMath\EvalMath;
+
 /**
-*  Implements hook_help().
-*  
-*/
+ *  Implements hook_help().
+ */
 function formula_field_help($path, $arg) {
   switch ($path) {
     case "admin/help#formula_field":
@@ -17,8 +18,10 @@ function formula_field_help($path, $arg) {
       $output .= '<h3>' . t('How it works') . '</h3>';
       $output .= '<p>' . t('As new field type asociated to particular content type, the field will fetch all \'integer\' fields in that bundle and make them available to setup formula. Further based on formula, on node load result is displayed against the field value') . '</p>';
       $output .= '<p>' . t('Thanks for using Formula Field module. You can create basic formula models like addition, substraction, multiplication or division from values present in any bundle and calculates its value. The module also works fine with Entities, Entityforms, Webforms and Nodes.') . '</p>';
+      $output .= '<h3>' . t('Requirement') . '</h3>';
+      $output .= '<p>' .t('This module requires eval-math-master library, make sure to download ') .'<a href=https://github.com/dbojdo/eval-math>' .t('Eval Math Library.').'</a>' . '</p>';
+      $output .= '<p>' .t('Place the library inside sites > all > libraries > eval-math-libraries.') .'</p>';
       return $output;
-    break;
   }
 }
 
@@ -306,8 +309,9 @@ function formula_field_field_formatter_view($entity_type, $entity, $field, $inst
  * Implements hook_field_presave().
  */
 function formula_field_field_presave($entity_type, $entity, $field, $instance, $langcode, &$items) {
+  libraries_load('eval-math-master');
+  $evalObj = new EvalMath();
   foreach ($items as $delta => $item) {
-    $calculated_answer = 0;
     $main_formula = json_decode($instance['settings']['main_formula']);
     $op = '';
     if(!empty($main_formula)) {
@@ -324,11 +328,17 @@ function formula_field_field_presave($entity_type, $entity, $field, $instance, $
         }
       }
     }
-    $calculated_answer = eval("return ($op);");
+
+    $compute = function () use($op, $evalObj) {
+      return ($evalObj->evaluate(trim($op)));
+    };
+
+    $calculated_answer = $compute();
     $items[$delta]['answer'] = !empty($calculated_answer) ? $calculated_answer : 0;
   }
 }
 
+
 /**
  * Implements hook_field_is_empty().
  */
@@ -336,3 +346,17 @@ function formula_field_field_is_empty($item, $field) {
   // Return empty($item['answer']) ? TRUE : FALSE;.
   return FALSE;
 }
+
+/**
+ * Implements hook_libraries_info().
+ */
+function formula_field_libraries_info() {
+  $libraries['eval-math-master'] = array(
+    'name' => 'eval-math-master',
+    'vendor url' => 'https://www.twmagic.com/',
+    'download url' => 'https://github.com/dbojdo/eval-math.git',
+    'version' => '1.0',
+    'files' => array('php' => array('vendor/autoload.php')),
+  );
+  return $libraries;
+}