diff --git a/src/Dust/Evaluate/Evaluator.php b/src/Dust/Evaluate/Evaluator.php
old mode 100644
new mode 100755
index 097c51e..8ab9715
--- a/src/Dust/Evaluate/Evaluator.php
+++ b/src/Dust/Evaluate/Evaluator.php
@@ -5,23 +5,23 @@
 use Dust\Filter;
 class Evaluator {
     public $dust;
-    
+
     public $options;
-    
+
     public function __construct(\Dust\Dust $dust, $options = null) {
         if ($options === null) $options = new EvaluatorOptions();
         $this->dust = $dust;
         $this->options = $options;
     }
-    
+
     public function error(Ast\Ast $ast = null, $message = null) {
         throw new EvaluateException($ast, $message);
     }
-    
+
     public function evaluate(Ast\Body $source, $state) {
         return trim($this->evaluateBody($source, new Context($this, null, new State($state)), new Chunk($this))->out);
     }
-    
+
     public function evaluateBody(Ast\Body $body, Context $ctx, Chunk $chunk) {
         //go ahead and set the file path on the current context
         $ctx->currentFilePath = $body->filePath;
@@ -35,7 +35,7 @@ public function evaluateBody(Ast\Body $body, Context $ctx, Chunk $chunk) {
         }
         return $chunk;
     }
-    
+
     public function evaluateSection(Ast\Section $section, Context $ctx, Chunk $chunk) {
         //stuff that doesn't need resolution
         if ($section->type == '+') {
@@ -63,7 +63,7 @@ public function evaluateSection(Ast\Section $section, Context $ctx, Chunk $chunk
             }
             //do we have the helper?
             if (!isset($this->dust->helpers[$section->identifier->key])) {
-                $this->error($section->identifier, 'Unable to find helper');
+                $this->error($section->identifier, 'Unable to find helper: ' . $section->identifier->key);
             }
             $helper = $this->dust->helpers[$section->identifier->key];
             //build state w/ no current value
@@ -135,7 +135,7 @@ public function evaluateSection(Ast\Section $section, Context $ctx, Chunk $chunk
         }
         return $chunk;
     }
-    
+
     public function evaluateElseBody(Ast\Section $section, Context $ctx, Chunk $chunk) {
         if ($section->bodies != null && count($section->bodies) > 0) {
             foreach ($section->bodies as $value) {
@@ -146,7 +146,7 @@ public function evaluateElseBody(Ast\Section $section, Context $ctx, Chunk $chun
         }
         return $chunk;
     }
-    
+
     public function evaluatePartial(Ast\Partial $partial, Context $ctx, Chunk $chunk) {
         $partialName = $partial->key;
         if ($partialName == null) $partialName = $this->toDustString($this->normalizeResolved($ctx, $partial->inline, $chunk));
@@ -179,7 +179,7 @@ public function evaluatePartial(Ast\Partial $partial, Context $ctx, Chunk $chunk
         //render the partial then
         return $this->evaluateBody($partialBody, $ctx->pushState($state), $chunk);
     }
-    
+
     public function evaluateSpecial(Ast\Special $spl, Context $ctx, Chunk $chunk) {
         switch ($spl->key) {
             case 'n':
@@ -202,7 +202,7 @@ public function evaluateSpecial(Ast\Special $spl, Context $ctx, Chunk $chunk) {
         }
         return $chunk;
     }
-    
+
     public function evaluateReference(Ast\Reference $ref, Context $ctx, Chunk $chunk) {
         //resolve
         $resolved = $this->normalizeResolved($ctx, $ctx->resolve($ref->identifier), $chunk);
@@ -229,12 +229,12 @@ public function evaluateReference(Ast\Reference $ref, Context $ctx, Chunk $chunk
         }
         return $chunk;
     }
-    
+
     public function evaluateBuffer(Ast\Buffer $buffer, Context $ctx, Chunk $chunk) {
         $chunk->write($buffer->contents);
         return $chunk;
     }
-    
+
     public function evaluateParameters(array $params, Context $ctx) {
         $ret = [];
         foreach ($params as $value) {
@@ -251,7 +251,7 @@ public function evaluateParameters(array $params, Context $ctx) {
         }
         return $ret;
     }
-    
+
     public function normalizeResolved(Context $ctx, $resolved, Chunk $chunk, Ast\Section $section = null) {
         $handledSpecial = true;
         while ($handledSpecial) {
@@ -274,14 +274,14 @@ public function normalizeResolved(Context $ctx, $resolved, Chunk $chunk, Ast\Sec
         }
         return $resolved;
     }
-    
+
     public function isEmpty($val) {
         //numeric not empty
         if (is_numeric($val)) return false;
         //otherwise, normal empty check
         return empty($val);
     }
-    
+
     public function exists($val) {
         //object exists
         if (is_object($val)) return true;
@@ -296,14 +296,14 @@ public function exists($val) {
         //nulls do not exist
         return !is_null($val);
     }
-    
+
     public function toDustString($val) {
         if (is_bool($val)) return $val ? 'true' : 'false';
         if (is_array($val)) return implode(',', $val);
         if (is_object($val) && !method_exists($val, '__toString')) return get_class($val);
         return (string) $val;
     }
-    
+
     public function handleCallback(Context $ctx, $callback, Chunk $chunk, Ast\Section $section = null) {
         //reset "this" on closures
         if ($callback instanceof \Closure) {
@@ -341,5 +341,5 @@ public function handleCallback(Context $ctx, $callback, Chunk $chunk, Ast\Sectio
         //invoke
         return call_user_func_array($callback, $args);
     }
-    
+
 }
\ No newline at end of file
diff --git a/tests/Dust/StandardTest.php b/tests/Dust/StandardTest.php
old mode 100644
new mode 100755
index 464f473..02a3589
--- a/tests/Dust/StandardTest.php
+++ b/tests/Dust/StandardTest.php
@@ -28,15 +28,15 @@ public function testContextTypes() {
         //class
         $this->assertTemplate($expected, $template, new StoogesContext());
     }
-    
+
     public function testArrayAccess() {
         $this->assertTemplate('123', '{#items}{.}{/items}', (object)["items" => new \ArrayObject([1, 2, 3])]);
     }
-    
+
     public function testStringIndex() {
         $this->assertTemplate('a => b,2 => c,foo => blah', '{#items}{$idx} => {.}{@sep},{/sep}{/items}', ["items" => ["a" => 'b', 2 => 'c', "foo" => 'blah']]);
     }
-    
+
     public function testAutoloaderOverride() {
         //override
         $autoloaderInvoked = false;
@@ -53,12 +53,12 @@ public function testAutoloaderOverride() {
         ]);
         $this->assertTrue($autoloaderInvoked);
     }
-    
+
     public function testCustomFilter() {
         $this->dust->filters['stripTags'] = new StripTagsFilter();
         $this->assertTemplate('Value: foo, bar', 'Value: {contents|stripTags}', (object)["contents" => '<div>foo, <br /><strong>bar</strong></div>']);
     }
-    
+
     public function testCustomHelper() {
         //from manual
         $this->dust->helpers['substr'] = function (Evaluate\Chunk $chunk, Evaluate\Context $ctx, Evaluate\Bodies $bodies, Evaluate\Parameters $params) {
@@ -77,5 +77,13 @@ public function testCustomHelper() {
         //test some things (kinda taken from PHP manual)
         $this->assertTemplate('bcdef,bcd,abcd,abcdef,bc', '{@substr str="abcdef" begin=1 /},' . '{@substr str="abcdef" begin=1 len=3 /},' . '{@substr str="abcdef" len=4 /},' . '{@substr str="abcdef" len=8 /},' . '{@substr str="abcdef" begin=1 end=3 /}', (object)[]);
     }
-    
+
+    public function testCustomHelperNotFound() {
+        try {
+            $this->assertTemplate('NULL', '{@customHelper param=myParam/}', (object)[]);
+        } catch (Evaluate\EvaluateException $exc) {
+            $this->assertEquals('Unable to find helper: customHelper', $exc->getMessage());
+        }
+    }
+
 }
\ No newline at end of file