diff --git a/configure.ac b/configure.ac
index 21a87194f4770c6b72d3c04ea39075c2e83491b2..bbee7b0612505071186f1ef57c54e6aa8271496b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -339,6 +339,18 @@ eval dynlib_suffix=$shrext_cmds
 AC_SUBST(dynlib_suffix)
 
 
+# Do we have GNU tar?
+AC_MSG_CHECKING([if you have GNU tar])
+if $tar --version 2> /dev/null | grep -q GNU; then
+    AC_MSG_RESULT(yes)
+    tarFlags="--warning=no-timestamp"
+else
+    AC_MSG_RESULT(no)
+fi
+AC_SUBST(tarFlags)
+
+
+
 AM_CONFIG_HEADER([config.h])
 AC_CONFIG_FILES([Makefile
    src/Makefile
diff --git a/corepkgs/config.nix.in b/corepkgs/config.nix.in
index 26e821d0e2d7cc871085f47f8cf2e0913eabc77f..6f6ec6de1a306a2f2521732bbf9e0f525450a4f6 100644
--- a/corepkgs/config.nix.in
+++ b/corepkgs/config.nix.in
@@ -9,6 +9,7 @@ in {
   bzip2 = "@bzip2@";
   xz = "@xz@";
   tar = "@tar@";
+  tarFlags = "@tarFlags@";
   tr = "@tr@";
   curl = "@curl@";
   nixBinDir = fromEnv "NIX_BIN_DIR" "@bindir@";
diff --git a/corepkgs/unpack-channel.nix b/corepkgs/unpack-channel.nix
index b26bece30eae24665ddec8d1649688b3fc4e0a34..bbc54c7d1e0dc92813fd2a30398fc66bae1a400d 100644
--- a/corepkgs/unpack-channel.nix
+++ b/corepkgs/unpack-channel.nix
@@ -6,7 +6,7 @@ let
     ''
       mkdir $out
       cd $out
-      ${bzip2} -d < $src | ${tar} xf -
+      ${bzip2} -d < $src | ${tar} xf - --warning=no-timestamp 
       mv * $out/$channelName
     '';
 
diff --git a/substitute.mk b/substitute.mk
index 77c5afc281179e8938b879fe736754dd58310e1e..378751943a7ef2a89795c6299ed1c9c6c3b15152 100644
--- a/substitute.mk
+++ b/substitute.mk
@@ -22,6 +22,7 @@
 	 -e "s^@coreutils\@^$(coreutils)^g" \
 	 -e "s^@sed\@^$(sed)^g" \
 	 -e "s^@tar\@^$(tar)^g" \
+	 -e "s^@tarFlags\@^$(tarFlags)^g" \
 	 -e "s^@gzip\@^$(gzip)^g" \
 	 -e "s^@pv\@^$(pv)^g" \
 	 -e "s^@tr\@^$(tr)^g" \