diff --git a/lib/Cake/Test/Case/Utility/DebuggerTest.php b/lib/Cake/Test/Case/Utility/DebuggerTest.php
index 99499295ab7..dfb823e8d5b 100644
--- a/lib/Cake/Test/Case/Utility/DebuggerTest.php
+++ b/lib/Cake/Test/Case/Utility/DebuggerTest.php
@@ -408,6 +408,11 @@ public function testExportVar() {
 false
 TEXT;
 		$this->assertTextEquals($expected, $result);
+
+		$file = fopen('php://output', 'w');
+		fclose($file);
+		$result = Debugger::exportVar($file);
+		$this->assertTextEquals('unknown', $result);
 	}
 
 /**
diff --git a/lib/Cake/Utility/Debugger.php b/lib/Cake/Utility/Debugger.php
index e1b5c2aecf2..865ee422998 100644
--- a/lib/Cake/Utility/Debugger.php
+++ b/lib/Cake/Utility/Debugger.php
@@ -500,6 +500,8 @@ protected static function _export($var, $depth, $indent) {
 				return strtolower(gettype($var));
 			case 'null':
 				return 'null';
+			case 'unknown':
+				return 'unknown';
 			default:
 				return self::_object($var, $depth - 1, $indent + 1);
 		}