diff --git a/system/core/Security.php b/system/core/Security.php
index 368e17d..6f5f5cb 100644
--- a/system/core/Security.php
+++ b/system/core/Security.php
@@ -884,7 +884,7 @@
 	{
 		if ($this->_csrf_hash === '')
 		{
-			// If the cookie exists we will use it's value.
+			// If the cookie exists we will use its value.
 			// We don't necessarily want to regenerate it with
 			// each page load since a page could contain embedded
 			// sub-pages causing this feature to fail
@@ -894,7 +894,7 @@
 				return $this->_csrf_hash = $_COOKIE[$this->_csrf_cookie_name];
 			}
 
-			$this->_csrf_hash = md5(uniqid(rand(), TRUE));
+			$this->_csrf_hash = md5(uniqid(mt_rand(), TRUE));
 			$this->csrf_set_cookie();
 		}
 
diff --git a/system/database/DB_driver.php b/system/database/DB_driver.php
index 53decf0..618f366 100644
--- a/system/database/DB_driver.php
+++ b/system/database/DB_driver.php
@@ -1135,7 +1135,7 @@
 				else
 				{
 					/* We have no other choice but to just get the first element's key.
-					 * Due to array_shift() accepting it's argument by reference, if
+					 * Due to array_shift() accepting its argument by reference, if
 					 * E_STRICT is on, this would trigger a warning. So we'll have to
 					 * assign it first.
 					 */
diff --git a/system/helpers/captcha_helper.php b/system/helpers/captcha_helper.php
index 29911dc..ea46f97 100644
--- a/system/helpers/captcha_helper.php
+++ b/system/helpers/captcha_helper.php
@@ -126,9 +126,9 @@
 		// Determine angle and position
 		// -----------------------------------
 		$length	= strlen($word);
-		$angle	= ($length >= 6) ? rand(-($length-6), ($length-6)) : 0;
-		$x_axis	= rand(6, (360/$length)-16);
-		$y_axis = ($angle >= 0) ? rand($img_height, $img_width) : rand(6, $img_height);
+		$angle	= ($length >= 6) ? mt_rand(-($length-6), ($length-6)) : 0;
+		$x_axis	= mt_rand(6, (360/$length)-16);
+		$y_axis = ($angle >= 0) ? mt_rand($img_height, $img_width) : mt_rand(6, $img_height);
 
 		// Create image
 		// PHP.net recommends imagecreatetruecolor(), but it isn't always available
@@ -183,13 +183,13 @@
 		if ($use_font === FALSE)
 		{
 			$font_size = 5;
-			$x = rand(0, $img_width / ($length / 3));
+			$x = mt_rand(0, $img_width / ($length / 3));
 			$y = 0;
 		}
 		else
 		{
 			$font_size = 16;
-			$x = rand(0, $img_width / ($length / 1.5));
+			$x = mt_rand(0, $img_width / ($length / 1.5));
 			$y = $font_size + 2;
 		}
 
@@ -197,13 +197,13 @@
 		{
 			if ($use_font === FALSE)
 			{
-				$y = rand(0 , $img_height / 2);
+				$y = mt_rand(0 , $img_height / 2);
 				imagestring($im, $font_size, $x, $y, $word[$i], $colors['text']);
 				$x += ($font_size * 2);
 			}
 			else
 			{
-				$y = rand($img_height / 2, $img_height - 3);
+				$y = mt_rand($img_height / 2, $img_height - 3);
 				imagettftext($im, $font_size, $angle, $x, $y, $colors['text'], $font_path, $word[$i]);
 				$x += $font_size;
 			}
diff --git a/tests/codeigniter/core/Security_test.php b/tests/codeigniter/core/Security_test.php
index 3f6e3b0..433ad31 100644
--- a/tests/codeigniter/core/Security_test.php
+++ b/tests/codeigniter/core/Security_test.php
@@ -5,7 +5,7 @@
 	public function set_up()
 	{
 		// Set cookie for security test
-		$_COOKIE['ci_csrf_cookie'] = md5(uniqid(rand(), TRUE));
+		$_COOKIE['ci_csrf_cookie'] = md5(uniqid(mt_rand(), TRUE));
 
 		// Set config for Security class
 		$this->ci_set_config('csrf_protection', TRUE);