diff --git a/0001-system.runtime.caching-Remove-inappropropriate-use-o.patch b/0001-system.runtime.caching-Remove-inappropropriate-use-o.patch
new file mode 100644
index 0000000000..eca7c1d675
--- /dev/null
+++ b/0001-system.runtime.caching-Remove-inappropropriate-use-o.patch
@@ -0,0 +1,38 @@
+From ffb5c90e08d2f619b207c07c25b8551f52e9913e Mon Sep 17 00:00:00 2001
+From: Marek Safar <marek.safar@gmail.com>
+Date: Sat, 9 May 2015 12:24:20 +0200
+Subject: [PATCH] [system.runtime.caching] Remove inappropropriate use of
+ Marshal.SizeOf. Fixes #29667
+
+---
+ mcs/class/System.Runtime.Caching/ReferenceSources/SRef.cs | 9 ++++++---
+ 1 file changed, 6 insertions(+), 3 deletions(-)
+
+diff --git a/mcs/class/System.Runtime.Caching/ReferenceSources/SRef.cs b/mcs/class/System.Runtime.Caching/ReferenceSources/SRef.cs
+index ce0812b..644a2fc 100644
+--- a/mcs/class/System.Runtime.Caching/ReferenceSources/SRef.cs
++++ b/mcs/class/System.Runtime.Caching/ReferenceSources/SRef.cs
+@@ -11,14 +11,17 @@ namespace System.Runtime.Caching {
+      */
+     internal class SRef {
+ 
+-        private Object _sizedRef;
++//        private Object _sizedRef;
+ 
+         internal SRef (Object target) {
+-            _sizedRef = target;
++//            _sizedRef = target;
+         }
+ 
+         internal long ApproximateSize {
+-            get { return (long) Marshal.SizeOf (_sizedRef.GetType ()); }
++            get {
++                // TODO: .net uses System.SizedReference which contains approximate size after Gen 2 collection
++                return 16;
++            }
+         }
+ 
+         internal void Dispose() {
+-- 
+1.9.1
+
diff --git a/mono-core.spec b/mono-core.spec
index 2e08853e3a..6f59346d2c 100644
--- a/mono-core.spec
+++ b/mono-core.spec
@@ -28,13 +28,14 @@
 
 Name:           mono-core
 Version:        4.0.1
-Release:        3
+Release:        4
 Summary:        Cross-platform, Open Source, .NET development framework
 License:        LGPL-2.1 and MIT and MS-PL
 Group:          Development/Languages/Mono
 Url:            http://www.mono-project.com
 Source0:        http://download.mono-project.com/sources/mono/mono-%{version}.tar.bz2
 Patch0:		import-amd64-tramp-size.patch
+Patch1:		0001-system.runtime.caching-Remove-inappropropriate-use-o.patch
 BuildRequires:  autoconf
 BuildRequires:  automake
 BuildRequires:  bison
@@ -119,6 +120,7 @@ technologies that have been submitted to the ECMA for standardization.
 %prep
 %setup -q -n mono-%{version}
 %patch0 -p1
+%patch1 -p1
 
 %build
 ./autogen.sh