diff --git a/layout/generic/nsVideoFrame.cpp b/layout/generic/nsVideoFrame.cpp
index 4731a6968e4a..ac57e4099110 100644
--- a/layout/generic/nsVideoFrame.cpp
+++ b/layout/generic/nsVideoFrame.cpp
@@ -92,7 +92,8 @@ nsVideoFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
     // And now have it update its internal state
     element->UpdateState(false);
 
-    UpdatePosterSource(false);
+    nsresult res = UpdatePosterSource(false);
+    NS_ENSURE_SUCCESS(res,res);
 
     if (!aElements.AppendElement(mPosterImage))
       return NS_ERROR_OUT_OF_MEMORY;
@@ -591,22 +592,20 @@ nsVideoFrame::GetVideoIntrinsicSize(nsRenderingContext *aRenderingContext)
                 nsPresContext::CSSPixelsToAppUnits(size.height));
 }
 
-void
+nsresult
 nsVideoFrame::UpdatePosterSource(bool aNotify)
 {
   NS_ASSERTION(HasVideoElement(), "Only call this on <video> elements.");
   HTMLVideoElement* element = static_cast<HTMLVideoElement*>(GetContent());
 
-  if (element->HasAttr(kNameSpaceID_None, nsGkAtoms::poster)) {
-    nsAutoString posterStr;
-    element->GetPoster(posterStr);
-    mPosterImage->SetAttr(kNameSpaceID_None,
-                          nsGkAtoms::src,
-                          posterStr,
-                          aNotify);
-  } else {
-    mPosterImage->UnsetAttr(kNameSpaceID_None, nsGkAtoms::poster, aNotify);
-  }
+  nsAutoString posterStr;
+  element->GetPoster(posterStr);
+  nsresult res = mPosterImage->SetAttr(kNameSpaceID_None,
+                                       nsGkAtoms::src,
+                                       posterStr,
+                                       aNotify);
+  NS_ENSURE_SUCCESS(res,res);
+  return NS_OK;
 }
 
 NS_IMETHODIMP
@@ -615,7 +614,8 @@ nsVideoFrame::AttributeChanged(int32_t aNameSpaceID,
                                int32_t aModType)
 {
   if (aAttribute == nsGkAtoms::poster && HasVideoElement()) {
-    UpdatePosterSource(true);
+    nsresult res = UpdatePosterSource(true);
+    NS_ENSURE_SUCCESS(res,res);
   }
   return nsContainerFrame::AttributeChanged(aNameSpaceID,
                                             aAttribute,
diff --git a/layout/generic/nsVideoFrame.h b/layout/generic/nsVideoFrame.h
index 67e058119521..03f9caf478b5 100644
--- a/layout/generic/nsVideoFrame.h
+++ b/layout/generic/nsVideoFrame.h
@@ -112,7 +112,7 @@ protected:
   // Sets the mPosterImage's src attribute to be the video's poster attribute,
   // if we're the frame for a video element. Only call on frames for video
   // elements, not for frames for audio elements.
-  void UpdatePosterSource(bool aNotify);
+  nsresult UpdatePosterSource(bool aNotify);
 
   virtual ~nsVideoFrame();
 
diff --git a/layout/generic/test/mochitest.ini b/layout/generic/test/mochitest.ini
index 58a03ca58a23..89146c9a5045 100644
--- a/layout/generic/test/mochitest.ini
+++ b/layout/generic/test/mochitest.ini
@@ -79,7 +79,6 @@ support-files = bug633762_iframe.html
 [test_bug831780.html]
 [test_bug841361.html]
 [test_bug904810.html]
-[test_bug938772.html]
 [test_contained_plugin_transplant.html]
 [test_image_selection.html]
 [test_image_selection_2.html]
diff --git a/layout/generic/test/test_bug938772.html b/layout/generic/test/test_bug938772.html
deleted file mode 100644
index de15eb6e5155..000000000000
--- a/layout/generic/test/test_bug938772.html
+++ /dev/null
@@ -1,23 +0,0 @@
-<!doctype html>
-<html>
-<!--
-https://bugzilla.mozilla.org/show_bug.cgi?id=938772
--->
-<title>Test for Bug 938772</title>
-<script src="/tests/SimpleTest/SimpleTest.js"></script>
-<link rel="stylesheet" href="/tests/SimpleTest/test.css">
-<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=938772">Mozilla Bug 938772</a>
-<p id="display"></p>
-<iframe id="i"
-        src="data:text/html,<base href='http://basetag/basetag'><video id='v' onerror='v.failed=true'></video>"></iframe>
-<pre id="test">
-<script>
-SimpleTest.waitForExplicitFinish();
-
-i.onload = function() {
-  ok(!i.contentDocument.getElementById("v").failed,
-     "Check whether an error was reported");
-  SimpleTest.finish();
-};
-</script>
-
