diff --git a/extras/FSTools.php b/extras/FSTools.php
index 7b5e7619..a37273a5 100644
--- a/extras/FSTools.php
+++ b/extras/FSTools.php
@@ -68,7 +68,7 @@ class FSTools
         }
         // Loop through the folder
         $dir = $this->dir($source);
-        while (false !== $entry = $dir->read()) {
+        while ( false !== ($entry = $dir->read()) ) {
             // Skip pointers
             if ($entry == '.' || $entry == '..') {
                 continue;
diff --git a/library/HTMLPurifier/ConfigSchema/Interchange/Directive.php b/library/HTMLPurifier/ConfigSchema/Interchange/Directive.php
index 688939a0..302d7921 100644
--- a/library/HTMLPurifier/ConfigSchema/Interchange/Directive.php
+++ b/library/HTMLPurifier/ConfigSchema/Interchange/Directive.php
@@ -38,7 +38,8 @@ class HTMLPurifier_ConfigSchema_Interchange_Directive
     public $allowed;
     
     /**
-     * List of aliases for the directive, e.g. array('Alt.Directive').
+     * List of aliases for the directive,
+     * e.g. array(new HTMLPurifier_ConfigSchema_Interchange_Id('Ns', 'Dir'))).
      */
     public $aliases = array();
     
diff --git a/maintenance/common.php b/maintenance/common.php
index 52e00453..eb57300e 100644
--- a/maintenance/common.php
+++ b/maintenance/common.php
@@ -2,9 +2,9 @@
 
 function assertCli() {
     if (php_sapi_name() != 'cli' && !getenv('PHP_IS_CLI')) {
-        echo 'Script cannot be called from web-browser (if you are calling via cli,
+        echo 'Script cannot be called from web-browser (if you are indeed calling via cli,
 set environment variable PHP_IS_CLI to work around this).';
-        exit;
+        exit(1);
     }
 }
 
diff --git a/maintenance/flush-definition-cache.php b/maintenance/flush-definition-cache.php
index 22037620..d0ebaba5 100755
--- a/maintenance/flush-definition-cache.php
+++ b/maintenance/flush-definition-cache.php
@@ -22,8 +22,7 @@ if (isset($argv[1])) {
     if (in_array($argv[1], $names)) {
         $names = array($argv[1]);
     } else {
-        echo "Did not recognized cache parameter {$argv[1]} as valid cache, aborting.\n";
-        exit;
+        throw new Exception("Cache parameter {$argv[1]} is not a valid cache");
     }
 }
 
diff --git a/maintenance/flush.php b/maintenance/flush.php
index 0d92f13f..325edf45 100644
--- a/maintenance/flush.php
+++ b/maintenance/flush.php
@@ -13,8 +13,9 @@ assertCli();
 
 function e($cmd) {
     echo "\$ $cmd\n";
-    passthru($cmd);
+    passthru($cmd, $status);
     echo "\n";
+    if ($status) exit($status);
 }
 
 e('php generate-includes.php');
diff --git a/maintenance/generate-includes.php b/maintenance/generate-includes.php
index 129fb5e4..d8295bd0 100644
--- a/maintenance/generate-includes.php
+++ b/maintenance/generate-includes.php
@@ -27,6 +27,7 @@ $exclude_files = array(
 // Determine what files need to be included:
 echo 'Scanning for files... ';
 $raw_files = $FS->globr('.', '*.php');
+if (!$raw_files) throw new Exception('Did not find any PHP source files');
 $files = array();
 foreach ($raw_files as $file) {
     $file = substr($file, 2); // rm leading './'
diff --git a/maintenance/generate-schema-cache.php b/maintenance/generate-schema-cache.php
index a61615c9..04c5f2bf 100644
--- a/maintenance/generate-schema-cache.php
+++ b/maintenance/generate-schema-cache.php
@@ -16,6 +16,7 @@ $target = '../library/HTMLPurifier/ConfigSchema/schema.ser';
 $FS = new FSTools();
 
 $files = $FS->globr('../library/HTMLPurifier/ConfigSchema/schema', '*.txt');
+if (!$files) throw new Exception('Did not find any schema files');
 
 $parser      = new HTMLPurifier_StringHashParser();
 $builder     = new HTMLPurifier_ConfigSchema_InterchangeBuilder();