diff --git a/.gitignore b/.gitignore
index d3dedb4..be97a71 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 mksh-R40d.cpio.gz
 /mksh_40.9.20120630.orig.tar.gz
+/mksh-R41.tgz
diff --git a/mksh.spec b/mksh.spec
index 0cec9c2..e11abda 100644
--- a/mksh.spec
+++ b/mksh.spec
@@ -1,17 +1,16 @@
 %define _bindir   /bin
-%global snapshot  20120630
 Summary:          MirBSD enhanced version of the Korn Shell
 Name:             mksh
-Version:          40i
-Release:          0%{?dist}.%{snapshot}
+Version:          41
+Release:          1%{?dist}
 # BSD (setmode.c), ISC (strlcpy.c), MirOS (the rest)
 License:          MirOS and ISC and BSD
 Group:            System Environment/Shells
 URL:              http://www.mirbsd.de/%{name}.htm
-Source0:          ftp://ftp.debian.org/debian/pool/main/m/%{name}/%{name}_40.9.%{snapshot}.orig.tar.gz
-#Source0:          http://www.mirbsd.org/MirOS/dist/mir/%{name}/%{name}-R%{version}.cpio.gz
+Source0:          http://www.mirbsd.org/MirOS/dist/mir/%{name}/%{name}-R%{version}.tgz
 Source1:          dot-mkshrc
 Source2:          lksh.1
+Source3:          rtchecks.expected
 Requires(post):   grep
 Requires(postun): sed
 BuildRequires:    util-linux, ed
@@ -25,18 +24,37 @@ modern, robust shell good for interactive and especially script use, being a
 bourne shell replacement, pdksh successor and an alternative to the C shell.
 
 %prep
-%setup -q -T -c
+#%setup -q -T -c
+%setup -q -n %{name}
 
-# rpm.org has no support for *.cpio.gz
-#gzip -dc %{SOURCE0} | cpio -imd
-#mv %{name}/* . && rm -rf %{name}
-tar xvzf %{SOURCE0}
-mv mksh-40.9.%{snapshot}.orig/* . 
+# we'll need this later due to -DMKSH_GCC55009
+cat >rtchecks <<'EOF'
+typeset -i sari=0
+typeset -Ui uari=0
+typeset -i x=0
+print -r -- $((x++)):$sari=$uari.
+let --sari --uari
+print -r -- $((x++)):$sari=$uari.
+sari=2147483647 uari=2147483647
+print -r -- $((x++)):$sari=$uari.
+let ++sari ++uari
+print -r -- $((x++)):$sari=$uari.
+let --sari --uari
+let 'sari *= 2' 'uari *= 2'
+let ++sari ++uari
+print -r -- $((x++)):$sari=$uari.
+let ++sari ++uari
+print -r -- $((x++)):$sari=$uari.
+sari=-2147483648 uari=-2147483648
+print -r -- $((x++)):$sari=$uari.
+let --sari --uari
+print -r -- $((x++)):$sari=$uari.
+EOF
 
 %build
-CFLAGS="$RPM_OPT_FLAGS" sh Build.sh -r -c lto
+CFLAGS="$RPM_OPT_FLAGS -DMKSH_DISABLE_EXPERIMENTAL -DMKSH_GCC55009" sh Build.sh -r -c lto
 cp test.sh test_mksh.sh
-CFLAGS="$RPM_OPT_FLAGS" sh Build.sh -L -r -c lto
+CFLAGS="$RPM_OPT_FLAGS -DMKSH_DISABLE_EXPERIMENTAL -DMKSH_GCC55009" sh Build.sh -L -r -c lto
 cp test.sh test_lksh.sh
 
 %install
@@ -49,6 +67,14 @@ install -D -p -m 644 dot.mkshrc $RPM_BUILD_ROOT%{_sysconfdir}/mkshrc
 install -D -p -m 644 %{SOURCE1} $RPM_BUILD_ROOT%{_sysconfdir}/skel/.mkshrc
 
 %check
+./mksh rtchecks >rtchecks.got 2>&1
+if ! cmp --quiet rtchecks.got %{SOURCE3}
+then
+  echo "rtchecks failed"
+  diff -Naurp %{SOURCE3} rtchecks.got
+  exit 1
+fi
+
 for tf in test_mksh.sh test_lksh.sh
 do
   echo > test.wait
@@ -84,6 +110,9 @@ rm -rf $RPM_BUILD_ROOT
 %{_mandir}/man1/lksh.1*
 
 %changelog
+* Mon Dec 03 2012 Michal Hlavinka <mhlavink@redhat.com> - 41-1
+- Upgrade to 41
+
 * Fri Jul 20 2012 Michal Hlavinka <mhlavink@redhat.com> - 40i-0.20120630
 - Upgrade to pre-release of 40i
 - includes new legacy shell lksh for old scripts requiring pdksh or similar old
diff --git a/rtchecks.expected b/rtchecks.expected
new file mode 100644
index 0000000..0d9a267
--- /dev/null
+++ b/rtchecks.expected
@@ -0,0 +1,8 @@
+0:0=0.
+1:-1=4294967295.
+2:2147483647=2147483647.
+3:-2147483648=2147483648.
+4:-1=4294967295.
+5:0=0.
+6:-2147483648=2147483648.
+7:2147483647=2147483647.
diff --git a/sources b/sources
index 99b8b4e..a4f2891 100644
--- a/sources
+++ b/sources
@@ -1 +1 @@
-d2da844ef5ae1c6c68d0675a4d0c1229  mksh_40.9.20120630.orig.tar.gz
+70eca50d9340412714ef09b7060ebde9  mksh-R41.tgz