diff --git a/docs/reference/gobject/gobject-sections.txt b/docs/reference/gobject/gobject-sections.txt
index 81db1b576..bed38e4c5 100644
--- a/docs/reference/gobject/gobject-sections.txt
+++ b/docs/reference/gobject/gobject-sections.txt
@@ -65,7 +65,6 @@ g_type_default_interface_unref
 g_type_children
 g_type_interfaces
 g_type_interface_prerequisites
-g_type_interface_instantiable_prerequisite
 g_type_set_qdata
 g_type_get_qdata
 g_type_query
diff --git a/gobject/gclosure.c b/gobject/gclosure.c
index 601dab1fd..472f037e2 100644
--- a/gobject/gclosure.c
+++ b/gobject/gclosure.c
@@ -1258,12 +1258,8 @@ static void
 value_from_ffi_type (GValue *gvalue, gpointer *value)
 {
   ffi_arg *int_val = (ffi_arg*) value;
-  GType type;
 
-  type = G_VALUE_TYPE (gvalue);
-
-restart:
-  switch (g_type_fundamental (type))
+  switch (g_type_fundamental (G_VALUE_TYPE (gvalue)))
     {
     case G_TYPE_INT:
       g_value_set_int (gvalue, (gint) *int_val);
@@ -1322,15 +1318,9 @@ restart:
     case G_TYPE_VARIANT:
       g_value_take_variant (gvalue, *(gpointer*)value);
       break;
-    case G_TYPE_INTERFACE:
-      type = g_type_interface_instantiable_prerequisite (G_VALUE_TYPE (gvalue));
-      if (type)
-        goto restart;
-      G_GNUC_FALLTHROUGH;
     default:
-      g_warning ("value_from_ffi_type: Unsupported fundamental type %s for type %s",
-                 g_type_name (g_type_fundamental (G_VALUE_TYPE (gvalue))),
-                 g_type_name (G_VALUE_TYPE (gvalue)));
+      g_warning ("value_from_ffi_type: Unsupported fundamental type: %s",
+                g_type_name (g_type_fundamental (G_VALUE_TYPE (gvalue))));
     }
 }
 
diff --git a/gobject/gtype.c b/gobject/gtype.c
index 94b3667bc..b5ef2d11e 100644
--- a/gobject/gtype.c
+++ b/gobject/gtype.c
@@ -1689,51 +1689,6 @@ g_type_interface_prerequisites (GType  interface_type,
     }
 }
 
-/**
- * g_type_interface_instantiable_prerequisite:
- * @interface_type: an interface type
- *
- * Returns the instantiable prerequisite of an interface type.
- *
- * If the interface type has no instantiable prerequisite, 0 is returned.
- *
- * Since: 2.64
- *
- * Returns: the instantiable prerequisite type or 0 if none
- **/
-GType
-g_type_interface_instantiable_prerequisite (GType interface_type)
-{
-  TypeNode *inode = NULL;
-  TypeNode *iface;
-  guint i;
-
-  g_return_val_if_fail (G_TYPE_IS_INTERFACE (interface_type), G_TYPE_INVALID);
-
-  iface = lookup_type_node_I (interface_type);
-  if (iface == NULL)
-    return 0;
-
-  G_READ_LOCK (&type_rw_lock);
-
-  for (i = 0; i < IFACE_NODE_N_PREREQUISITES (iface); i++)
-    {
-      GType prerequisite = IFACE_NODE_PREREQUISITES (iface)[i];
-      TypeNode *node = lookup_type_node_I (prerequisite);
-      if (node->is_instantiatable)
-        {
-          if (!inode || type_node_is_a_L (node, inode))
-            inode = node;
-        }
-    }
-
-  G_READ_UNLOCK (&type_rw_lock);
-
-  if (inode)
-    return NODE_TYPE (inode);
-  else
-    return 0;
-}
 
 static IFaceHolder*
 type_iface_peek_holder_L (TypeNode *iface,
@@ -3452,7 +3407,7 @@ g_type_depth (GType type)
  * @root_type: immediate parent of the returned type
  *
  * Given a @leaf_type and a @root_type which is contained in its
- * ancestry, return the type that @root_type is the immediate parent
+ * anchestry, return the type that @root_type is the immediate parent
  * of. In other words, this function determines the type that is
  * derived directly from @root_type which is also a base class of
  * @leaf_type.  Given a root type and a leaf type, this function can
diff --git a/gobject/gtype.h b/gobject/gtype.h
index b092f7f2b..797ab48ee 100644
--- a/gobject/gtype.h
+++ b/gobject/gtype.h
@@ -1304,9 +1304,6 @@ void  g_type_interface_add_prerequisite (GType			     interface_type,
 GLIB_AVAILABLE_IN_ALL
 GType*g_type_interface_prerequisites    (GType                       interface_type,
 					 guint                      *n_prerequisites);
-GLIB_AVAILABLE_IN_2_64
-GType g_type_interface_instantiable_prerequisite
-                                        (GType                       interface_type);
 GLIB_DEPRECATED_IN_2_58
 void     g_type_class_add_private       (gpointer                    g_class,
                                          gsize                       private_size);
diff --git a/gobject/gvalue.c b/gobject/gvalue.c
index df7b4ee11..c30501a6b 100644
--- a/gobject/gvalue.c
+++ b/gobject/gvalue.c
@@ -448,15 +448,6 @@ g_value_init_from_instance (GValue  *value,
     }
 }
 
-static GType
-tranform_lookup_get_parent_type (GType type)
-{
-  if (g_type_fundamental (type) == G_TYPE_INTERFACE)
-    return g_type_interface_instantiable_prerequisite (type);
-
-  return g_type_parent (type);
-}
-
 static GValueTransform
 transform_func_lookup (GType src_type,
 		       GType dest_type)
@@ -479,11 +470,11 @@ transform_func_lookup (GType src_type,
 		  g_type_value_table_peek (entry.src_type) == g_type_value_table_peek (src_type))
 		return e->func;
 	    }
-	  entry.dest_type = tranform_lookup_get_parent_type (entry.dest_type);
+	  entry.dest_type = g_type_parent (entry.dest_type);
 	}
       while (entry.dest_type);
       
-      entry.src_type = tranform_lookup_get_parent_type (entry.src_type);
+      entry.src_type = g_type_parent (entry.src_type);
     }
   while (entry.src_type);
 
diff --git a/gobject/tests/type.c b/gobject/tests/type.c
index 9ed1806e9..c5db7e992 100644
--- a/gobject/tests/type.c
+++ b/gobject/tests/type.c
@@ -52,7 +52,6 @@ test_interface_prerequisite (void)
   g_assert_cmpint (n_prereqs, ==, 2);
   g_assert (prereqs[0] == bar_get_type ());
   g_assert (prereqs[1] == G_TYPE_OBJECT);
-  g_assert (g_type_interface_instantiable_prerequisite (foo_get_type ()) == G_TYPE_OBJECT);
 
   iface = g_type_default_interface_ref (foo_get_type ());
   parent = g_type_interface_peek_parent (iface);