diff --git a/core/ManifestBuilder.php b/core/ManifestBuilder.php
index 6fffe9ab5..c31084bf3 100644
--- a/core/ManifestBuilder.php
+++ b/core/ManifestBuilder.php
@@ -219,8 +219,8 @@ class ManifestBuilder {
 
 				// Skip certain directories
 				if($filename[0] == '.') continue;
-				if($filename == 'themes') continue;
-				if($filename == 'assets') continue;
+				if($filename == THEMES_DIR) continue;
+				if($filename == ASSETS_DIR) continue;
 				if(in_array($filename, $excludedFolders)) continue;
 
 				if(@is_dir("$baseDir/$filename") &&
@@ -246,7 +246,7 @@ class ManifestBuilder {
 			$themeDirs = self::get_themes("$baseDir/themes", true);
 			foreach($themeDirs as $themeDir) {
 				$themeName = strtok($themeDir, '_');
-				ManifestBuilder::getTemplateManifest($baseDir, "themes/$themeDir", $excludedFolders, $templateManifest, $cssManifest, $themeName);
+				ManifestBuilder::getTemplateManifest($baseDir, THEMES_DIR . "/$themeDir", $excludedFolders, $templateManifest, $cssManifest, $themeName);
 			}
 		}
 
diff --git a/core/Requirements.php b/core/Requirements.php
index 9184823ad..feae98c0a 100644
--- a/core/Requirements.php
+++ b/core/Requirements.php
@@ -395,11 +395,10 @@ class Requirements_Backend {
 	public $combine_js_with_jsmin = true;
 
 	/**
-	 * By default, combined files are stored in assets/_combinedfiles.
+	 * @var string By default, combined files are stored in assets/_combinedfiles.
 	 * Set this by calling Requirements::set_combined_files_folder()
-	 * @var string
 	 */
-	protected $combinedFilesFolder = 'assets/_combinedfiles';
+	protected $combinedFilesFolder = null;
 
 	/**
 	 * Put all javascript includes at the bottom of the template
@@ -424,10 +423,20 @@ class Requirements_Backend {
 		return $this->combined_files_enabled;
 	}
 
+	/**
+	 * @param String $folder
+	 */
 	function setCombinedFilesFolder($folder) {
 		$this->combinedFilesFolder = $folder;
 	}
 	
+	/**
+	 * @return String Folder relative to the webroot
+	 */
+	function getCombinedFilesFolder() {
+		return ($this->combinedFilesFolder) ? $this->combinedFilesFolder : ASSETS_DIR . '/_combinedfiles';
+	}
+	
 	/**
 	 * Set whether we want to suffix requirements with the time / 
 	 * location on to the requirements
@@ -849,7 +858,7 @@ class Requirements_Backend {
 	 */
 	function delete_combined_files($combinedFileName = null) {
 		$combinedFiles = ($combinedFileName) ? array($combinedFileName => null) : $this->combine_files;
-		$combinedFolder = ($this->combinedFilesFolder) ? (Director::baseFolder() . '/' . $this->combinedFilesFolder) : Director::baseFolder();
+		$combinedFolder = ($this->getCombinedFilesFolder()) ? (Director::baseFolder() . '/' . $this->combinedFilesFolder) : Director::baseFolder();
 		foreach($combinedFiles as $combinedFile => $sourceItems) {
 			$filePath = $combinedFolder . '/' . $combinedFile;
 			if(file_exists($filePath)) {
@@ -889,7 +898,7 @@ class Requirements_Backend {
 		}
 
 		// Work out the relative URL for the combined files from the base folder
-		$combinedFilesFolder = ($this->combinedFilesFolder) ? ($this->combinedFilesFolder . '/') : '';
+		$combinedFilesFolder = ($this->getCombinedFilesFolder()) ? ($this->getCombinedFilesFolder() . '/') : '';
 
 		// Figure out which ones apply to this pageview
 		$combinedFiles = array();
@@ -917,7 +926,7 @@ class Requirements_Backend {
 		$base = Director::baseFolder() . '/';
 		foreach(array_diff_key($combinedFiles, $this->blocked) as $combinedFile => $dummy) {
 			$fileList = $this->combine_files[$combinedFile];
-			$combinedFilePath = $base . $this->combinedFilesFolder . '/' . $combinedFile;
+			$combinedFilePath = $base . $combinedFilesFolder . '/' . $combinedFile;
 
 
 			// Make the folder if necessary
diff --git a/core/model/Image.php b/core/model/Image.php
index 7facb2067..d8900d570 100755
--- a/core/model/Image.php
+++ b/core/model/Image.php
@@ -333,7 +333,7 @@ class Image extends File {
 		$methodNames = $this->allMethodNames();
 		$cachedFiles = array();
 		
-		$folder = $this->ParentID ? $this->Parent()->Filename : 'assets/';
+		$folder = $this->ParentID ? $this->Parent()->Filename : ASSETS_DIR . '/';
 		$cacheDir = Director::getAbsFile($folder . '_resampled/');
 		
 		if(is_dir($cacheDir)) {
diff --git a/filesystem/File.php b/filesystem/File.php
index 8a004b4ab..792d4af48 100755
--- a/filesystem/File.php
+++ b/filesystem/File.php
@@ -87,7 +87,7 @@ class File extends DataObject {
 		$item = null;
 
 		foreach($parts as $part) {
-			if($part == "assets" && !$parentID) continue;
+			if($part == ASSETS_DIR && !$parentID) continue;
 			$SQL_part = Convert::raw2sql($part);
 			$item = DataObject::get_one("File", "\"Name\" = '$SQL_part' AND \"ParentID\" = $parentID");
 			if(!$item) break;