diff --git a/configure.in b/configure.in
index d18b2f0da2..f74d472ac4 100644
--- a/configure.in
+++ b/configure.in
@@ -11,9 +11,9 @@ AC_PREREQ(2.62)
 # set GTK_BINARY_AGE and GTK_INTERFACE_AGE to 0.
 
 m4_define([gtk_major_version], [2])
-m4_define([gtk_minor_version], [20])
-m4_define([gtk_micro_version], [1])
-m4_define([gtk_interface_age], [1])
+m4_define([gtk_minor_version], [21])
+m4_define([gtk_micro_version], [0])
+m4_define([gtk_interface_age], [0])
 m4_define([gtk_binary_age],
           [m4_eval(100 * gtk_minor_version + gtk_micro_version)])
 m4_define([gtk_version],