diff --git a/diffutils-cmp-s-empty.patch b/diffutils-cmp-s-empty.patch
new file mode 100644
index 0000000..bc1c6b4
--- /dev/null
+++ b/diffutils-cmp-s-empty.patch
@@ -0,0 +1,20 @@
+diff -up diffutils-2.8.1/src/cmp.c.cmp-s-empty diffutils-2.8.1/src/cmp.c
+--- diffutils-2.8.1/src/cmp.c.cmp-s-empty	2002-04-05 21:37:31.000000000 +0100
++++ diffutils-2.8.1/src/cmp.c	2010-06-25 14:56:08.464802321 +0100
+@@ -316,12 +316,15 @@ main (int argc, char **argv)
+ 
+   /* If only a return code is needed,
+      and if both input descriptors are associated with plain files,
++     and if both files are larger than 0 bytes (procfs files are always 0),
+      conclude that the files differ if they have different sizes
+      and if more bytes will be compared than are in the smaller file.  */
+ 
+   if (comparison_type == type_status
+       && S_ISREG (stat_buf[0].st_mode)
+-      && S_ISREG (stat_buf[1].st_mode))
++      && S_ISREG (stat_buf[1].st_mode)
++      && stat_buf[0].st_size > 0
++      && stat_buf[1].st_size > 0)
+     {
+       off_t s0 = stat_buf[0].st_size - file_position (0);
+       off_t s1 = stat_buf[1].st_size - file_position (1);
diff --git a/diffutils.spec b/diffutils.spec
index e669483..b111178 100644
--- a/diffutils.spec
+++ b/diffutils.spec
@@ -1,7 +1,7 @@
 Summary: A GNU collection of diff utilities
 Name: diffutils
 Version: 2.8.1
-Release: 25%{?dist}
+Release: 26%{?dist}
 Group: Applications/Text
 URL: http://www.gnu.org/software/diffutils/diffutils.html
 Source: ftp://ftp.gnu.org/gnu/diffutils/diffutils-%{version}.tar.gz
@@ -13,6 +13,7 @@ Patch0: diffutils-2.8.4-i18n.patch
 Patch1: diffutils-2.8.1-badc.patch
 Patch2: diffutils-sdiff.patch
 Patch3: diffutils-sdiff-E.patch
+Patch4: diffutils-cmp-s-empty.patch
 License: GPLv2+
 Requires(post): /sbin/install-info
 Requires(preun): /sbin/install-info
@@ -37,6 +38,7 @@ Install diffutils if you need to compare text files.
 %patch1 -p1 -b .badc
 %patch2 -p1 -b .sdiff
 %patch3 -p1 -b .sdiff-E
+%patch4 -p1 -b .cmp-s-empty
 
 %build
 %configure
@@ -81,6 +83,9 @@ rm -rf $RPM_BUILD_ROOT
 %{_infodir}/diff.info*gz
 
 %changelog
+* Fri Jun 25 2010 Tim Waugh <twaugh@redhat.com> 2.8.1-26
+- For 'cmp -s', compare file sizes only if both non-zero (bug #563618).
+
 * Tue Aug 11 2009 Tim Waugh <twaugh@redhat.com> 2.8.1-25
 - Only try to install the info file if it exists so that package
   installation does not fail with --excludedocs (bug #515919).