diff --git a/rubygem-gdk3.spec b/rubygem-gdk3.spec
index 57cbe48..65e9891 100644
--- a/rubygem-gdk3.spec
+++ b/rubygem-gdk3.spec
@@ -68,35 +68,18 @@ BuildArch:	noarch
 Documentation for %{name}
 
 %prep
-%setup -q -c -T
-
-TOPDIR=$(pwd)
-mkdir tmpunpackdir
-pushd tmpunpackdir
-
-gem unpack %{SOURCE0}
-cd %{gem_name}-%{version}
-
+%setup -q -n %{gem_name}-%{version}
+mv ../%{gem_name}-%{version}.gemspec .
 #Patches
 
 # Permission
 find . -name \*.rb -print0 | xargs --null chmod 0644
 
-gem specification -l --ruby %{SOURCE0} > %{gem_name}.gemspec
-
-# Allow ruby-gnome2 no less than ones
-sed -i -e 's|= 3\.4\.9|>= 3.4.9|' %{gem_name}.gemspec
-sed -i -e '\@s\.extensions@d'  %{gem_name}.gemspec
-
-gem build %{gem_name}.gemspec
-mv %{gem_name}-%{version}.gem $TOPDIR
-
-popd
-rm -rf tmpunpackdir
+sed -i -e 's|= 3\.4\.9|>= 3.4.9|' %{gem_name}-%{version}.gemspec
+sed -i -e '\@s\.extensions@d'  %{gem_name}-%{version}.gemspec
 
 %build
-mkdir -p .%{gem_dir}
-
+gem build %{gem_name}-%{version}.gemspec
 %gem_install
 
 %install