diff --git a/inc/functions.php b/inc/functions.php
index 97e2a802..b6b5f16e 100644
--- a/inc/functions.php
+++ b/inc/functions.php
@@ -211,6 +211,23 @@
 		} else return false;
 	}
 	
+	function file_write($path, $data) {
+		$fp = fopen($path, 'c');
+
+		// File locking
+		if(!flock($fp, LOCK_EX)) {
+			error('Unable to lock file!');
+		}
+		
+		// Truncate file
+		ftruncate($fp, 0);
+		// Write data
+		fwrite($fp, $data);
+		flock($fp, LOCK_UN);
+
+		fclose($fp);
+	}
+	
 	function listBoards() {
 		$query = query("SELECT * FROM `boards` ORDER BY `uri`") or error(db_error());
 		$boards = $query->fetchAll();
@@ -972,7 +989,7 @@
 			$content['pages'][$page-1]['selected'] = true;
 			$content['btn'] = getPageButtons($content['pages']);
 			$content['hidden_inputs'] = createHiddenInputs();
-			@file_put_contents($filename, Element('index.html', $content)) or error("Couldn't write to file.");
+			file_write($filename, Element('index.html', $content));
 			
 			if(isset($md5) && $md5 == md5_file($filename)) {
 				break;
@@ -997,7 +1014,7 @@
 				'uri' => addslashes((!empty($uri) ? $config['uri_stylesheets'] : '') . $uri));
 		}
 		
-		file_put_contents($config['file_script'], Element('main.js', Array(
+		file_write($config['file_script'], Element('main.js', Array(
 			'config' => $config,
 			'stylesheets' => $stylesheets
 		)));
@@ -1269,7 +1286,7 @@
 		if($return)
 			return $body;
 		else
-			@file_put_contents($board['dir'] . $config['dir']['res'] . sprintf($config['file_page'], $id), $body) or error("Couldn't write to file.");
+			file_write($board['dir'] . $config['dir']['res'] . sprintf($config['file_page'], $id), $body);
 	}
 	
 	 function rrmdir($dir) {
diff --git a/install.php b/install.php
index c6a89da3..74482a08 100644
--- a/install.php
+++ b/install.php
@@ -66,7 +66,7 @@
 				}
 				
 				// Update version number
-				file_put_contents($config['has_installed'], VERSION);
+				file_write($config['has_installed'], VERSION);
 				
 				$page['title'] = 'Upgraded';
 				$page['body'] = '<p style="text-align:center">Successfully upgraded from ' . $version . ' to <strong>' . VERSION . '</strong>.</p>';
@@ -401,7 +401,7 @@
 		if(!empty($sql_errors)) {
 			$page['body'] .= '<div class="ban"><h2>SQL errors</h2><p>SQL errors were encountered when trying to install the database. This may be the result of using a database which is already occupied with a Tinyboard installation; if so, you can probably ignore this.</p><p>The errors encountered were:</p><ul>' . $sql_errors . '</ul><p><a href="?step=5">Ignore errors and complete installation.</a></p></div>';
 		} else {
-			file_put_contents($config['has_installed'], VERSION);
+			file_write($config['has_installed'], VERSION);
 			if(!@unlink(__FILE__)) {
 				$page['body'] .= '<div class="ban"><h2>Delete install.php!</h2><p>I couldn\'t remove <strong>install.php</strong>. You will have to remove it manually.</p></div>';
 			}
@@ -412,7 +412,7 @@
 		$page['title'] = 'Installation complete';
 		$page['body'] = '<p style="text-align:center">Thank you for using Tinyboard. Please remember to report any bugs you discover.</p>';
 		
-		file_put_contents($config['has_installed'], VERSION);
+		file_write($config['has_installed'], VERSION);
 		if(!@unlink(__FILE__)) {
 			$page['body'] .= '<div class="ban"><h2>Delete install.php!</h2><p>I couldn\'t remove <strong>install.php</strong>. You will have to remove it manually.</p></div>';
 		}