diff --git a/gtk/tools/gtk-builder-tool-simplify.c b/gtk/tools/gtk-builder-tool-simplify.c
index 06a31fb2b9..9d96c85e09 100644
--- a/gtk/tools/gtk-builder-tool-simplify.c
+++ b/gtk/tools/gtk-builder-tool-simplify.c
@@ -733,6 +733,7 @@ maybe_rename_property (Element *element, MyParserData *data)
     { "GtkWidget", "margin-left", GTK_TYPE_WIDGET, PROP_KIND_OBJECT, "margin-start", { NULL, NULL, NULL } },
     { "GtkWidget", "margin-right", GTK_TYPE_WIDGET, PROP_KIND_OBJECT, "margin-end", { NULL, NULL, NULL } },
     { "GtkHeaderBar", "show-close-button", GTK_TYPE_HEADER_BAR, PROP_KIND_OBJECT, "show-title-buttons", { NULL, NULL, NULL } },
+    { "GtkHeaderBar", "custom-title", GTK_TYPE_HEADER_BAR, PROP_KIND_OBJECT, "title-widget", { NULL, NULL, NULL } },
     { "GtkStack", "homogeneous", GTK_TYPE_STACK, PROP_KIND_OBJECT, "hhomogeneous", { "vhomogeneous", NULL, NULL } }
   };
   int i, k, l;
diff --git a/testsuite/tools/simplify-data-3to4/headerbar.expected b/testsuite/tools/simplify-data-3to4/headerbar.expected
new file mode 100644
index 0000000000..d987f58a68
--- /dev/null
+++ b/testsuite/tools/simplify-data-3to4/headerbar.expected
@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <object class="GtkWindow" id="window1">
+    <child type="titlebar">
+      <object class="GtkHeaderBar" id="headerbar1">
+        <property name="show-title-buttons">1</property>
+        <property name="title-widget">box1</property>
+      </object>
+    </child>
+  </object>
+  <object class="GtkBox" id="box1"/>
+</interface>
diff --git a/testsuite/tools/simplify-data-3to4/headerbar.ui b/testsuite/tools/simplify-data-3to4/headerbar.ui
new file mode 100644
index 0000000000..9ad70329d7
--- /dev/null
+++ b/testsuite/tools/simplify-data-3to4/headerbar.ui
@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <!-- interface-requires gtk+ 3.0 -->
+  <object class="GtkWindow" id="window1">
+    <child type="titlebar">
+      <object class="GtkHeaderBar" id="headerbar1">
+        <property name="visible">True</property>
+        <property name="show-close-button">True</property>
+        <property name="custom-title">box1</property>
+      </object>
+    </child>
+  </object>
+  <object class="GtkBox" id="box1">
+    <property name="visible">True</property>
+  </object>
+</interface>