diff --git a/configure.in b/configure.in
index 1301bac..f43b88b 100644
--- a/configure.in
+++ b/configure.in
@@ -1,4 +1,4 @@
-AC_INIT([Zenity],[2.31.3],[http://bugzilla.gnome.org/enter_bug.cgi?product=zenity],[zenity])
+AC_INIT([Zenity],[2.31.5],[http://bugzilla.gnome.org/enter_bug.cgi?product=zenity],[zenity])
 
 AC_PREREQ([2.59])
 
@@ -18,9 +18,9 @@ IT_PROG_INTLTOOL([0.40.0])
 
 AC_PROG_CC
 
-GTK_REQUIRED=2.15.1
+GTK_REQUIRED=2.90.2
 
-PKG_CHECK_MODULES([ZENITY],[gtk+-2.0 >= $GTK_REQUIRED glib-2.0])
+PKG_CHECK_MODULES([ZENITY],[gtk+-3.0 >= $GTK_REQUIRED glib-2.0])
 AC_SUBST([ZENITY_CFLAGS])
 AC_SUBST([ZENITY_LIBS])
 
@@ -30,7 +30,7 @@ dnl *************************
 
 zenity_save_cflags="$CFLAGS"
 # pull in the CFLAGS to locate gdkconfig.h
-CFLAGS=`$PKG_CONFIG --cflags gtk+-2.0`
+CFLAGS=`$PKG_CONFIG --cflags gtk+-3.0`
 AC_COMPILE_IFELSE([
 #include <gdkconfig.h>