diff --git a/ChangeLog b/ChangeLog
index f6465ac673..d62764592f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2007-06-26  Johan Dahlin  <jdahlin@async.com.br>
 
+	* gtk/gtkbuilder.h (enum): 
+	* gtk/gtkbuilderparser.c (end_element): 
+	* tests/buildertest.c (test_parser): 
+	Set an error if we encounter properties without values set
+	(#451303, Philip Withnall)
+	
 	* demos/gtk-demo/builder.c (do_builder): Connect the
 	destroy signal in the example instead of the ui file.
 	Also set the screen and title of the window.
diff --git a/gtk/gtkbuilder.h b/gtk/gtkbuilder.h
index 767d7220ad..36348b25ac 100644
--- a/gtk/gtkbuilder.h
+++ b/gtk/gtkbuilder.h
@@ -43,7 +43,8 @@ typedef enum
   GTK_BUILDER_ERROR_UNHANDLED_TAG,
   GTK_BUILDER_ERROR_MISSING_ATTRIBUTE,
   GTK_BUILDER_ERROR_INVALID_ATTRIBUTE,
-  GTK_BUILDER_ERROR_INVALID_TAG
+  GTK_BUILDER_ERROR_INVALID_TAG,
+  GTK_BUILDER_ERROR_MISSING_PROPERTY_VALUE
 } GtkBuilderError;
 
 GQuark gtk_builder_error_quark (void);
diff --git a/gtk/gtkbuilderparser.c b/gtk/gtkbuilderparser.c
index 25b3479946..ea2df67e64 100644
--- a/gtk/gtkbuilderparser.c
+++ b/gtk/gtkbuilderparser.c
@@ -139,6 +139,24 @@ error_invalid_tag (ParserData *data,
 		 line_number, char_number, tag);
 }
 
+static void
+error_missing_property_value (ParserData *data,
+			      GError **error)
+{
+  gint line_number, char_number;
+
+  g_markup_parse_context_get_position (data->ctx,
+                                       &line_number,
+                                       &char_number);
+
+  g_set_error (error,
+	       GTK_BUILDER_ERROR,
+	       GTK_BUILDER_ERROR_MISSING_PROPERTY_VALUE,
+	       "%s:%d:%d <property> must have a value set",
+	       data->filename,
+	       line_number, char_number);
+}
+
 static GObject *
 builder_construct (ParserData *data,
                    ObjectInfo *object_info)
@@ -707,6 +725,12 @@ end_element (GMarkupParseContext *context,
       PropertyInfo *prop_info = state_pop_info (data, PropertyInfo);
       CommonInfo *info = state_peek_info (data, CommonInfo);
 
+      if (!prop_info->data)
+	{
+	  error_missing_property_value (data, error);
+	  return;
+	}
+      
       /* Normal properties */
       if (strcmp (info->tag.name, "object") == 0)
         {
diff --git a/tests/buildertest.c b/tests/buildertest.c
index 3c6ab29b17..3367bdcd1f 100644
--- a/tests/buildertest.c
+++ b/tests/buildertest.c
@@ -72,6 +72,13 @@ gboolean test_parser (void)
   g_return_val_if_fail (strcmp (error->message, "<input>:1:74 'object' is not a valid tag here") == 0, FALSE);
   g_error_free (error);
 
+  error = NULL;
+  gtk_builder_add_from_string (builder, "<interface><object class=\"GtkWindow\" id=\"a\"><property name=\"type\"/></object></interface>", -1, &error);
+  g_assert (error != NULL);
+  g_return_val_if_fail (strcmp (error->message, "<input>:1:67 <property> must have a value set") == 0, FALSE);
+  g_error_free (error);
+
+  
   return TRUE;
 }