diff --git a/filesystem/Folder.php b/filesystem/Folder.php
index 60c70f6c4..4984d34c0 100755
--- a/filesystem/Folder.php
+++ b/filesystem/Folder.php
@@ -250,6 +250,15 @@ class Folder extends File {
 			$i++;
 			$oldFile = $file;
 			$file = "$origFile-$i";
+			
+			if(strpos($file, '.') !== false) {
+				$file = ereg_replace('[0-9]*(\.[^.]+$)',$i . '\\1', $file);
+			} else if (strpos($file, '_') !== false) {
+				$file = ereg_replace('_([^_]+$)', '_'.$i, $file);
+			} else {
+				$file .= "_$i";
+			}
+			
 			if($oldFile == $file && $i > 2) user_error("Couldn't fix $file$ext with $i", E_USER_ERROR);
 		}
 		
diff --git a/filesystem/Upload.php b/filesystem/Upload.php
index c76fbfec0..44addfe90 100644
--- a/filesystem/Upload.php
+++ b/filesystem/Upload.php
@@ -127,8 +127,12 @@ class Upload extends Controller {
 			if(substr($relativeFilePath, strlen($relativeFilePath) - strlen('.tar.gz')) == '.tar.gz' ||
 				substr($relativeFilePath, strlen($relativeFilePath) - strlen('.tar.bz2')) == '.tar.bz2') {
 					$relativeFilePath = ereg_replace('[0-9]*(\.tar\.[^.]+$)',$i . '\\1', $relativeFilePath);
-			} else {
+			} else if (strpos($relativeFilePath, '.') !== false) {
 				$relativeFilePath = ereg_replace('[0-9]*(\.[^.]+$)',$i . '\\1', $relativeFilePath);
+			} else if (strpos($relativeFilePath, '_') !== false) {
+				$relativeFilePath = ereg_replace('_([^_]+$)', '_'.$i, $relativeFilePath);
+			} else {
+				$relativeFilePath .= "_$i";
 			}
 			if($oldFilePath == $relativeFilePath && $i > 2) user_error("Couldn't fix $relativeFilePath with $i tries", E_USER_ERROR);
 		}
@@ -433,7 +437,13 @@ class Upload_Validator {
 	 */
 	public function isValidExtension() {
 		$pathInfo = pathinfo($this->tmpFile['name']);
-		return (!count($this->allowedExtensions) || in_array(strtolower($pathInfo['extension']), $this->allowedExtensions));
+		
+		// Special case for filenames with an extension
+		if(!isset($pathInfo['extension'])) {
+			return (in_array('', $this->allowedExtensions, true)) ? true : false;
+		} else {
+			return (!count($this->allowedExtensions) || in_array(strtolower($pathInfo['extension']), $this->allowedExtensions));
+		}
 	}	
 	
 	/**
diff --git a/tests/filesystem/UploadTest.php b/tests/filesystem/UploadTest.php
index 77f12e29b..e21bea865 100644
--- a/tests/filesystem/UploadTest.php
+++ b/tests/filesystem/UploadTest.php
@@ -127,6 +127,124 @@ class UploadTest extends SapphireTest {
 		$file->delete();
 	}
 	
+	function testUploadDeniesNoExtensionFilesIfNoEmptyStringSetForValidatorExtensions() {
+		// create tmp file
+		$tmpFileName = 'UploadTest_testUpload';
+		$tmpFilePath = TEMP_FOLDER . '/' . $tmpFileName;
+		$tmpFileContent = '';
+		for($i=0; $i<10000; $i++) $tmpFileContent .= '0';
+		file_put_contents($tmpFilePath, $tmpFileContent);
+		
+		// emulates the $_FILES array
+		$tmpFile = array(
+			'name' => $tmpFileName,
+			'type' => 'text/plaintext',
+			'size' => filesize($tmpFilePath),
+			'tmp_name' => $tmpFilePath,
+			'extension' => 'txt',
+			'error' => UPLOAD_ERR_OK,
+		);
+
+		$v = new UploadTest_Validator();
+		$v->setAllowedExtensions(array('txt'));
+		
+		// test upload into default folder
+		$u = new Upload();
+		$result = $u->load($tmpFile);
+		
+		$this->assertFalse($result, 'Load failed because extension was not accepted');
+		$this->assertEquals(1, count($u->getErrors()), 'There is a single error of the file extension');
+		
+	}
+	
+	function testUploadTarGzFileTwiceAppendsNumber() {
+		// create tmp file
+		$tmpFileName = 'UploadTest_testUpload.tar.gz';
+		$tmpFilePath = TEMP_FOLDER . '/' . $tmpFileName;
+		$tmpFileContent = '';
+		for($i=0; $i<10000; $i++) $tmpFileContent .= '0';
+		file_put_contents($tmpFilePath, $tmpFileContent);
+		
+		// emulates the $_FILES array
+		$tmpFile = array(
+			'name' => $tmpFileName,
+			'type' => 'text/plaintext',
+			'size' => filesize($tmpFilePath),
+			'tmp_name' => $tmpFilePath,
+			'extension' => 'txt',
+			'error' => UPLOAD_ERR_OK,
+		);
+		
+		// test upload into default folder
+		$u = new Upload();
+		$u->load($tmpFile);
+		$file = $u->getFile();
+		$this->assertEquals(
+			'UploadTesttestUpload.tar.gz',
+			$file->Name,
+			'File has a name without a number because it\'s not a duplicate'
+		);
+		
+		$u = new Upload();
+		$u->load($tmpFile);
+		$file2 = $u->getFile();
+		$this->assertEquals(
+			'UploadTesttestUpload2.tar.gz',
+			$file2->Name,
+			'File receives a number attached to the end before the extension'
+		);
+		
+		$file->delete();
+		$file2->delete();
+	}
+	
+	function testUploadFileWithNoExtensionTwiceAppendsNumber() {
+		// create tmp file
+		$tmpFileName = 'UploadTest_testUpload';
+		$tmpFilePath = TEMP_FOLDER . '/' . $tmpFileName;
+		$tmpFileContent = '';
+		for($i=0; $i<10000; $i++) $tmpFileContent .= '0';
+		file_put_contents($tmpFilePath, $tmpFileContent);
+		
+		// emulates the $_FILES array
+		$tmpFile = array(
+			'name' => $tmpFileName,
+			'type' => 'text/plaintext',
+			'size' => filesize($tmpFilePath),
+			'tmp_name' => $tmpFilePath,
+			'extension' => 'txt',
+			'error' => UPLOAD_ERR_OK,
+		);
+		
+		$v = new UploadTest_Validator();
+		$v->setAllowedExtensions(array(''));
+		
+		// test upload into default folder
+		$u = new Upload();
+		$u->setValidator($v);
+		$u->load($tmpFile);
+		$file = $u->getFile();
+		
+		$this->assertEquals(
+			'UploadTesttestUpload',
+			$file->Name,
+			'File is uploaded without extension'
+		);
+		
+		$u = new Upload();
+		$u->setValidator($v);
+		$u->load($tmpFile);
+		$file2 = $u->getFile();
+		$this->assertEquals(
+			'UploadTesttestUpload_2',
+			$file2->Name,
+			'File receives a number attached to the end'
+		);
+		
+		$file->delete();
+		$file2->delete();
+	}
+
 }
 class UploadTest_Validator extends Upload_Validator implements TestOnly {