diff --git a/configure.ac b/configure.ac
index 28f8df5d..b4b74937 100644
--- a/configure.ac
+++ b/configure.ac
@@ -21,7 +21,7 @@ dnl LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 dnl OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 dnl WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 AC_PREREQ(2.61)
-AC_INIT([spdylay], [0.3.3], [t-tujikawa@users.sourceforge.net])
+AC_INIT([spdylay], [0.3.4-DEV], [t-tujikawa@users.sourceforge.net])
 LT_PREREQ([2.2.6])
 LT_INIT()
 dnl See versioning rule: