diff --git a/data/gui/manage_bookmarks_window.ui b/data/gui/manage_bookmarks_window.ui
index 7be3b9cfb..f61987d6c 100644
--- a/data/gui/manage_bookmarks_window.ui
+++ b/data/gui/manage_bookmarks_window.ui
@@ -51,6 +51,7 @@
                   <object class="GtkHButtonBox" id="hbuttonbox25">
                     <property name="visible">True</property>
                     <property name="spacing">6</property>
+                    <property name="layout_style">center</property>
                     <child>
                       <object class="GtkButton" id="add_bookmark_button">
                         <property name="label">gtk-add</property>
diff --git a/data/gui/manage_proxies_window.ui b/data/gui/manage_proxies_window.ui
index c1092e697..ce1b419a2 100644
--- a/data/gui/manage_proxies_window.ui
+++ b/data/gui/manage_proxies_window.ui
@@ -64,6 +64,7 @@
                   <object class="GtkHButtonBox" id="hbuttonbox21">
                     <property name="visible">True</property>
                     <property name="spacing">6</property>
+                    <property name="layout_style">center</property>
                     <child>
                       <object class="GtkButton" id="add_proxy_button">
                         <property name="label">gtk-add</property>