diff --git a/src/mibew/libs/classes/Mibew/Maintenance/Installer.php b/src/mibew/libs/classes/Mibew/Maintenance/Installer.php
index 5c3d61d9..3243011f 100644
--- a/src/mibew/libs/classes/Mibew/Maintenance/Installer.php
+++ b/src/mibew/libs/classes/Mibew/Maintenance/Installer.php
@@ -123,6 +123,11 @@ class Installer
             array(Utils::formatVersionId($this->getPhpVersionId()))
         );
 
+        if (!$this->checkPhpExtensions()) {
+            return false;
+        }
+        $this->log[] = getlocal('All necessary PHP extensions are loaded');
+
         if (!$this->checkFsPermissions()) {
             return false;
         }
@@ -476,6 +481,27 @@ class Installer
         return true;
     }
 
+    /**
+     * Checks that all necessary PHP extensions are loaded.
+     *
+     * @return boolean True if all necessary extensions are loaded and false
+     *   otherwise.
+     */
+    protected function checkPhpExtensions()
+    {
+        $extensions = array('PDO', 'pdo_mysql', 'gd', 'iconv');
+
+        foreach ($extensions as $ext) {
+            if (!extension_loaded($ext)) {
+                $this->errors[] = getlocal('PHP {0} extension is not loaded', array($ext));
+
+                return false;
+            }
+        }
+
+        return true;
+    }
+
     /**
      * Checks if files and directories permissions are correct.
      *