-# Compute minor/major version numbers
-major_version=`echo AC_PACKAGE_VERSION | sed 's/\..*//'`
-minor_version=`echo AC_PACKAGE_VERSION | sed 's/.*\.//' | sed 's/^0//'`
+
+# Compute minor/major/patchlevel version numbers
+AC_PROG_SED
+major_version=$(echo AC_PACKAGE_VERSION | sed 's/^\([[0-9]]\)*\.[[0-9]]*\.[[0-9]]*$/\1/')
+minor_version=$(echo AC_PACKAGE_VERSION | sed 's/^[[0-9]]*\.\([[0-9]]*\)\.[[0-9]]*$/\1/')
+patchlevel_version=$(echo AC_PACKAGE_VERSION | sed 's/^[[0-9]]*\.[[0-9]]*\.\([[0-9]]*\)$/\1/')