diff --git a/ChangeLog b/ChangeLog
index 785c01fafb..4f9a9c9aed 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,8 @@
 2008-02-29  Johan Dahlin  <johan@gnome.org>
 
 	* gtk/gtkbuilder.c:
+	Add missing g_return_val_if_fail checks for public API.
+
 	* gtk/gtkbuilderparser.c:
 	* gtk/gtkbuilderprivate.h:
 	Do not use g_error for a few more errors, instead set
diff --git a/gtk/gtkbuilder.c b/gtk/gtkbuilder.c
index 1c57048754..cc96135220 100644
--- a/gtk/gtkbuilder.c
+++ b/gtk/gtkbuilder.c
@@ -663,6 +663,7 @@ gtk_builder_add_from_file (GtkBuilder   *builder,
 
   g_return_val_if_fail (GTK_IS_BUILDER (builder), 0);
   g_return_val_if_fail (filename != NULL, 0);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
 
   tmp_error = NULL;
 
@@ -714,6 +715,7 @@ gtk_builder_add_from_string (GtkBuilder   *builder,
 
   g_return_val_if_fail (GTK_IS_BUILDER (builder), 0);
   g_return_val_if_fail (buffer != NULL, 0);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
 
   tmp_error = NULL;
 
@@ -1015,6 +1017,12 @@ gtk_builder_value_from_string (GtkBuilder   *builder,
                                GValue       *value,
 			       GError      **error)
 {
+  g_return_val_if_fail (GTK_IS_BUILDER (builder), FALSE);
+  g_return_val_if_fail (G_IS_PARAM_SPEC (pspec), FALSE);
+  g_return_val_if_fail (string != NULL, FALSE);
+  g_return_val_if_fail (value != NULL, FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
+
   /*
    * GParamSpecUnichar has the internal type G_TYPE_UINT,
    * so we cannot handle this in the switch, do it separately
@@ -1062,6 +1070,7 @@ gtk_builder_value_from_string_type (GtkBuilder   *builder,
 
   g_return_val_if_fail (type != G_TYPE_INVALID, FALSE);
   g_return_val_if_fail (string != NULL, FALSE);
+  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
 
   g_value_init (value, type);