diff --git a/application/controllers/upload.php b/application/controllers/upload.php
index d13a3a5..5669313 100644
--- a/application/controllers/upload.php
+++ b/application/controllers/upload.php
@@ -23,25 +23,34 @@ class Upload extends CI_Controller {
 			$message = array('type' => 'error', 'status' => $this->upload->display_errors());
 		} else {
 			$upload = $this->upload->data();
+			$hash = md5_file($upload['full_path']);
 
 			$this->load->model('fileupload');
-			$file_name = $this->fileupload->add_upload($upload['file_ext'], $upload['client_name']);
-			rename($upload['full_path'], $upload['file_path'] . $file_name . $upload['file_ext']);
+			$duplicate = $this->fileupload->check_duplicate($hash);
+			
+			if($duplicate) {
+				$message = array('type'=>'error', 'status'=>'file already exists:' . $duplicate);
+			} else {
+				$file_name = $this->fileupload->add_upload($upload['file_ext'], $upload['client_name'],$hash);
+				
+				rename($upload['full_path'], $upload['file_path'] . $file_name . $upload['file_ext']);
 
-			$config = array(
-				'image_library'			=> 'gd2',
-				'source_image'			=> $upload['file_path'] . $file_name . $upload['file_ext'],
-				'create_thumb'			=> true,
-				'maintain_ratio'		=> true,
-				'width'					=> 175,
-				'height'				=> 175,
-				'new_image'				=> './thumbs/' . $file_name . $upload['file_ext'],
-				'thumb_marker'			=> '',
-			);
+				$config = array(
+					'image_library'			=> 'gd2',
+					'source_image'			=> $upload['file_path'] . $file_name . $upload['file_ext'],
+					'create_thumb'			=> true,
+					'maintain_ratio'		=> true,
+					'width'					=> 175,
+					'height'				=> 175,
+					'new_image'				=> './thumbs/' . $file_name . $upload['file_ext'],
+					'thumb_marker'			=> '',
+				);
 
-			$this->load->library('image_lib',$config);
-			$this->image_lib->resize();
-			$message = array('type'=>'success','status'=>'Uploaded successfully', 'file'=>base_url($file_name));
+				$this->load->library('image_lib',$config);
+				$this->image_lib->resize();
+			
+				$message = array('type'=>'success','status'=>'Uploaded successfully', 'file'=>base_url($file_name));
+			}
 		}
 
 		echo json_encode($message);
diff --git a/application/models/fileupload.php b/application/models/fileupload.php
index 94c50a5..2927b99 100644
--- a/application/models/fileupload.php
+++ b/application/models/fileupload.php
@@ -5,10 +5,11 @@ class Fileupload extends CI_Model {
 		parent::__construct();
 	}
 
-	function add_upload($extension, $original_name) {
+	function add_upload($extension, $original_name, $hash) {
 		$data = array(
 			'extension'			=> $extension,
 			'original_name'		=> $original_name,
+			'hash'				=> $hash,
 		);
 
 		$this->db->insert('uploads', $data);
@@ -43,6 +44,19 @@ class Fileupload extends CI_Model {
 
 		return $query->result();
 	}
+
+	function check_duplicate($hash) {
+		$this->db->select('id')->from('uploads')->where('hash',$hash);
+		$query = $this->db->get();
+
+		if($query->num_rows == 0) {
+			return false;
+		} else {
+			$result = $query->result();
+
+			return $result[0]->id;
+		}
+	}
 }
 
 ?>
\ No newline at end of file