diff --git a/Makefile.am b/Makefile.am
index 2d10b20520..f2cb7e2afa 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -104,6 +104,6 @@ AM_DISTCHECK_CONFIGURE_FLAGS =		\
 	--enable-installed-tests
 
 GITIGNORE_TRANSLATION_DIRS = po-properties
-GITIGNOREFILES = po-properties/gtk30-properties.pot
+GITIGNOREFILES = po-properties/gtk40-properties.pot
 
 -include $(top_srcdir)/git.mk
diff --git a/configure.ac b/configure.ac
index afe7defc4b..c6b229f902 100644
--- a/configure.ac
+++ b/configure.ac
@@ -168,7 +168,7 @@ AC_USE_SYSTEM_EXTENSIONS
 AM_GNU_GETTEXT([external])
 AM_GNU_GETTEXT_VERSION([0.19.7])
 
-GETTEXT_PACKAGE=gtk30
+GETTEXT_PACKAGE=gtk40
 AC_SUBST(GETTEXT_PACKAGE)
 AC_DEFINE_UNQUOTED(GETTEXT_PACKAGE, "$GETTEXT_PACKAGE",
                    [The prefix for our gettext translation domains.])
diff --git a/demos/gtk-demo/listbox.ui b/demos/gtk-demo/listbox.ui
index 8e61227069..db0ce6e76c 100644
--- a/demos/gtk-demo/listbox.ui
+++ b/demos/gtk-demo/listbox.ui
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<interface domain="gtk30">
+<interface domain="gtk40">
   <!-- interface-requires gtk+ 3.10 -->
   <!-- interface-requires gtkdemo 3.10 -->
   <object class="GtkMenu" id="menu1">
diff --git a/docs/RELEASE-HOWTO b/docs/RELEASE-HOWTO
index 1c4d201280..b3c66ac247 100644
--- a/docs/RELEASE-HOWTO
+++ b/docs/RELEASE-HOWTO
@@ -28,8 +28,8 @@ Make sure that gtk-doc is the latest released version.
 
  3) Update the pot files and commit the changes:
 
-    make -C po gtk30.pot
-    make -C po-properties gtk30-properties.pot
+    make -C po gtk40.pot
+    make -C po-properties gtk40-properties.pot
 
  4) In particular, if this is a major, stable, release, verify that
     README.in contains the relevant release notes and that the
diff --git a/gtk/inspector/actions.ui b/gtk/inspector/actions.ui
index c87a06bac6..aa33bc0585 100644
--- a/gtk/inspector/actions.ui
+++ b/gtk/inspector/actions.ui
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<interface domain="gtk30">
+<interface domain="gtk40">
   <object class="GtkListStore" id="model">
     <columns>
       <column type="gchararray"/>
diff --git a/gtk/inspector/css-editor.ui b/gtk/inspector/css-editor.ui
index ad69197612..9bfd973a16 100644
--- a/gtk/inspector/css-editor.ui
+++ b/gtk/inspector/css-editor.ui
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<interface domain="gtk30">
+<interface domain="gtk40">
   <object class="GtkTextTagTable" id="tags">
     <child type="tag">
       <object class="GtkTextTag">
diff --git a/gtk/inspector/css-node-tree.ui b/gtk/inspector/css-node-tree.ui
index a40982ee4d..1fff833f7a 100644
--- a/gtk/inspector/css-node-tree.ui
+++ b/gtk/inspector/css-node-tree.ui
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<interface domain="gtk30">
+<interface domain="gtk40">
   <object class="GtkListStore" id="prop_model">
     <columns>
       <column type="gchararray"/>
diff --git a/gtk/inspector/data-list.ui b/gtk/inspector/data-list.ui
index b436213486..e9905532d7 100644
--- a/gtk/inspector/data-list.ui
+++ b/gtk/inspector/data-list.ui
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<interface domain="gtk30">
+<interface domain="gtk40">
   <template class="GtkInspectorDataList" parent="GtkBox">
     <property name="orientation">vertical</property>
     <child>
diff --git a/gtk/inspector/general.ui b/gtk/inspector/general.ui
index e2ff8e9250..527d63ed1b 100644
--- a/gtk/inspector/general.ui
+++ b/gtk/inspector/general.ui
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<interface domain="gtk30">
+<interface domain="gtk40">
   <template class="GtkInspectorGeneral" parent="GtkScrolledWindow">
     <property name="hscrollbar-policy">never</property>
     <property name="vscrollbar-policy">automatic</property>
diff --git a/gtk/inspector/magnifier.ui b/gtk/inspector/magnifier.ui
index e4264082c1..8bf7f62151 100644
--- a/gtk/inspector/magnifier.ui
+++ b/gtk/inspector/magnifier.ui
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<interface domain="gtk30">
+<interface domain="gtk40">
   <template class="GtkInspectorMagnifier" parent="GtkBox">
     <property name="orientation">vertical</property>
     <child>
diff --git a/gtk/inspector/menu.ui b/gtk/inspector/menu.ui
index 970bc6b29e..51cbf99756 100644
--- a/gtk/inspector/menu.ui
+++ b/gtk/inspector/menu.ui
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<interface domain="gtk30">
+<interface domain="gtk40">
   <object class="GtkTreeStore" id="model">
     <columns>
       <column type="gchararray"/> <!-- type -->
diff --git a/gtk/inspector/misc-info.ui b/gtk/inspector/misc-info.ui
index 0f1546a3b0..a5bc70d388 100644
--- a/gtk/inspector/misc-info.ui
+++ b/gtk/inspector/misc-info.ui
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<interface domain="gtk30">
+<interface domain="gtk40">
   <template class="GtkInspectorMiscInfo" parent="GtkScrolledWindow">
     <child>
       <object class="GtkBox">
diff --git a/gtk/inspector/object-hierarchy.ui b/gtk/inspector/object-hierarchy.ui
index 0f5c61b796..8afcb5cfdd 100644
--- a/gtk/inspector/object-hierarchy.ui
+++ b/gtk/inspector/object-hierarchy.ui
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<interface domain="gtk30">
+<interface domain="gtk40">
   <object class="GtkTreeStore" id="model">
     <columns>
       <column type="gchararray"/>
diff --git a/gtk/inspector/object-tree.ui b/gtk/inspector/object-tree.ui
index 95abc05f3c..0229a93bcd 100644
--- a/gtk/inspector/object-tree.ui
+++ b/gtk/inspector/object-tree.ui
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<interface domain="gtk30">
+<interface domain="gtk40">
   <object class="GtkTreeStore" id="model">
     <columns>
       <column type="gpointer"/>
diff --git a/gtk/inspector/prop-list.ui b/gtk/inspector/prop-list.ui
index f4892cc894..c1475a12a7 100644
--- a/gtk/inspector/prop-list.ui
+++ b/gtk/inspector/prop-list.ui
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<interface domain="gtk30">
+<interface domain="gtk40">
   <object class="GtkListStore" id="model">
     <columns>
       <column type="gchararray"/>
diff --git a/gtk/inspector/resource-list.ui b/gtk/inspector/resource-list.ui
index 2907a73ef4..5178a9280f 100644
--- a/gtk/inspector/resource-list.ui
+++ b/gtk/inspector/resource-list.ui
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<interface domain="gtk30">
+<interface domain="gtk40">
   <object class="GtkTreeStore" id="model">
     <columns>
       <column type="gchararray"/>
diff --git a/gtk/inspector/selector.ui b/gtk/inspector/selector.ui
index db008753b9..02278fa147 100644
--- a/gtk/inspector/selector.ui
+++ b/gtk/inspector/selector.ui
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<interface domain="gtk30">
+<interface domain="gtk40">
   <object class="GtkTreeStore" id="model">
     <columns>
       <column type="gchararray"/>
diff --git a/gtk/inspector/signals-list.ui b/gtk/inspector/signals-list.ui
index b173c24bb9..5710a6b6ba 100644
--- a/gtk/inspector/signals-list.ui
+++ b/gtk/inspector/signals-list.ui
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<interface domain="gtk30">
+<interface domain="gtk40">
   <object class="GtkListStore" id="model">
     <columns>
       <column type="gchararray"/>
diff --git a/gtk/inspector/statistics.ui b/gtk/inspector/statistics.ui
index b1ceefce4e..20e62618d4 100644
--- a/gtk/inspector/statistics.ui
+++ b/gtk/inspector/statistics.ui
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<interface domain="gtk30">
+<interface domain="gtk40">
   <object class="GtkListStore" id="model">
     <columns>
       <column type="GType"/>
diff --git a/gtk/inspector/visual.ui b/gtk/inspector/visual.ui
index 9f30af87bb..4bf1867042 100644
--- a/gtk/inspector/visual.ui
+++ b/gtk/inspector/visual.ui
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<interface domain="gtk30">
+<interface domain="gtk40">
   <object class="GtkAdjustment" id="scale_adjustment">
     <property name="lower">1</property>
     <property name="upper">2</property>
diff --git a/gtk/inspector/window.ui b/gtk/inspector/window.ui
index 33592cd9c3..c2a0ccfb5b 100644
--- a/gtk/inspector/window.ui
+++ b/gtk/inspector/window.ui
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<interface domain="gtk30">
+<interface domain="gtk40">
   <object class="GtkAdjustment" id="magnification_adjustment">
     <property name="lower">1.0</property>
     <property name="upper">5.0</property>
diff --git a/make-pot b/make-pot
index 1abb5905e3..e95e971f30 100755
--- a/make-pot
+++ b/make-pot
@@ -9,11 +9,11 @@
 #
 #   ./make-pot
 #
-# to generate po/gtk30.pot, and like this:
+# to generate po/gtk40.pot, and like this:
 #
 #   ./make-pot properties
 #
-# to generate po-properties/gtk30-properties.pot.
+# to generate po-properties/gtk40-properties.pot.
 #
 # Various things can be passed in by environment variables, which
 # are heavily inspired by the variables used in po/Makefile.in.in:
@@ -23,7 +23,7 @@
 # srcdir - the directory where POTFILES.in is located (defaults to
 #          $top_srcdir/po or $top_srcdir/po-properties)
 # GETTEXT_PACKAGE - the gettext domain, used for naming the resulting
-#          .pot file (defaults to gtk30 or gtk30-properties)
+#          .pot file (defaults to gtk40 or gtk40-properties)
 # XGETTEXT_KEYWORDS - --keyword arguments to pass to xgettext
 
 
@@ -32,11 +32,11 @@ top_srcdir="${top_srcdir:-.}"
 
 if test "$1" = "properties"; then
   srcdir="${srcdir:-$top_srcdir/po-properties}"
-  GETTEXT_PACKAGE="${GETTEXT_PACKAGE:-gtk30-properties}"
+  GETTEXT_PACKAGE="${GETTEXT_PACKAGE:-gtk40-properties}"
   XGETTEXT_KEYWORDS="${XGETTEXT_KEYWORDS:- --keyword --keyword=P_ }"
 else
   srcdir="${srcdir:-$top_srcdir/po}"
-  GETTEXT_PACKAGE="${GETTEXT_PACKAGE:-gtk30}"
+  GETTEXT_PACKAGE="${GETTEXT_PACKAGE:-gtk40}"
   XGETTEXT_KEYWORDS="${XGETTEXT_KEYWORDS:- --keyword=_ --keyword=N_ --keyword=C_:1c,2 --keyword=NC_:1c,2 --keyword=g_dngettext:2,3 }"
 fi
 
diff --git a/po-properties/Makevars b/po-properties/Makevars
index ad69e56628..38f3819091 100644
--- a/po-properties/Makevars
+++ b/po-properties/Makevars
@@ -1,7 +1,7 @@
 # Makefile variables for PO directory in any package using GNU gettext.
 
 # Usually the message domain is the same as the package name.
-DOMAIN = gtk30-properties
+DOMAIN = gtk40-properties
 
 # These two variables depend on the location of this directory.
 subdir = po
diff --git a/po/Makevars b/po/Makevars
index cc2d602284..d8c4fccdbb 100644
--- a/po/Makevars
+++ b/po/Makevars
@@ -1,7 +1,7 @@
 # Makefile variables for PO directory in any package using GNU gettext.
 
 # Usually the message domain is the same as the package name.
-DOMAIN = gtk30
+DOMAIN = gtk40
 
 # These two variables depend on the location of this directory.
 subdir = po