diff --git a/LayoutTests/ChangeLog b/LayoutTests/ChangeLog
index 281737b..d9d8a5c 100644
--- a/LayoutTests/ChangeLog
+++ b/LayoutTests/ChangeLog
@@ -1,3 +1,12 @@
+2013-10-30  Jer Noble  <jer.noble@apple.com>
+
+        REGRESSION(r158288): media/media-can-play-mpeg4-video.html fails
+        https://bugs.webkit.org/show_bug.cgi?id=123530
+
+        Reviewed by Eric Carlson.
+
+        * TestExpectations:
+
 2013-10-30  Santosh Mahto  <santosh.ma@samsung.com>
 
         contentEditable deleting lists when list items are block level
diff --git a/LayoutTests/TestExpectations b/LayoutTests/TestExpectations
index fd412c0..fba0e1a 100644
--- a/LayoutTests/TestExpectations
+++ b/LayoutTests/TestExpectations
@@ -75,5 +75,3 @@
 webkit.org/b/122679 security/crypto-subtle-gc.html [ Skip ]
 webkit.org/b/122679 security/crypto-subtle-gc-2.html [ Skip ]
 webkit.org/b/122679 security/crypto-subtle-gc-3.html [ Skip ]
-
-webkit.org/b/123530 media/media-can-play-mpeg4-video.html [ Failure ]
diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
index d72d160..88ef1cf 100644
--- a/Source/WebCore/ChangeLog
+++ b/Source/WebCore/ChangeLog
@@ -1,3 +1,16 @@
+2013-10-30  Jer Noble  <jer.noble@apple.com>
+
+        REGRESSION(r158288): media/media-can-play-mpeg4-video.html fails
+        https://bugs.webkit.org/show_bug.cgi?id=123530
+
+        Reviewed by Eric Carlson.
+
+        Lower case the mime type before passing it along to MediaPlayer.
+
+        * html/HTMLMediaElement.cpp:
+        (WebCore::HTMLMediaElement::canPlayType):
+        (WebCore::HTMLMediaElement::selectNextSourceChild):
+
 2013-10-30  Alexey Proskuryakov  <ap@apple.com>
 
         Add a way to fulfill promises from DOM code
diff --git a/Source/WebCore/html/HTMLMediaElement.cpp b/Source/WebCore/html/HTMLMediaElement.cpp
index 793bc4b..534c612 100644
--- a/Source/WebCore/html/HTMLMediaElement.cpp
+++ b/Source/WebCore/html/HTMLMediaElement.cpp
@@ -764,7 +764,7 @@
 {
     MediaEngineSupportParameters parameters;
     ContentType contentType(mimeType);
-    parameters.type = contentType.type();
+    parameters.type = contentType.type().lower();
     parameters.codecs = contentType.parameter(ASCIILiteral("codecs"));
     parameters.url = url;
 #if ENABLE(ENCRYPTED_MEDIA)
@@ -3533,7 +3533,7 @@
 #endif
             MediaEngineSupportParameters parameters;
             ContentType contentType(type);
-            parameters.type = contentType.type();
+            parameters.type = contentType.type().lower();
             parameters.codecs = contentType.parameter(ASCIILiteral("codecs"));
             parameters.url = mediaURL;
 #if ENABLE(ENCRYPTED_MEDIA)