diff --git a/lib/private/image.php b/lib/private/image.php
index 317b6fde1605..2484aeecc63f 100644
--- a/lib/private/image.php
+++ b/lib/private/image.php
@@ -283,9 +283,12 @@ public function resource() {
 	}
 
 	/**
-	 * @return string Returns the raw image data.
+	 * @return null|string Returns the raw image data.
 	 */
 	function data() {
+		if (!$this->valid()) {
+			return null;
+		}
 		ob_start();
 		switch ($this->mimeType) {
 			case "image/png":
diff --git a/tests/lib/image.php b/tests/lib/image.php
index e0009b9710eb..0ee517100ad5 100644
--- a/tests/lib/image.php
+++ b/tests/lib/image.php
@@ -144,6 +144,11 @@ public function testData() {
 		$this->assertEquals($expected, $img->data());
 	}
 
+	public function testDataNoResource() {
+		$img = new \OC_Image();
+		$this->assertNull($img->data());
+	}
+
 	/**
 	 * @depends testData
 	 */