diff --git a/src/base/ftbbox.c b/src/base/ftbbox.c
index 7dd71882e..385fea404 100644
--- a/src/base/ftbbox.c
+++ b/src/base/ftbbox.c
@@ -82,10 +82,13 @@
    * @Return:
    *   Always 0.  Needed for the interface only.
    */
-  static int
-  BBox_Move_To( FT_Vector*  to,
-                TBBox_Rec*  user )
+  FT_CALLBACK_DEF( int )
+  BBox_Move_To( const FT_Vector*  to,
+                void*             user_ )
   {
+    TBBox_Rec*  user = (TBBox_Rec*)user_;
+
+
     FT_UPDATE_BBOX( to, user->bbox );
 
     user->last = *to;
@@ -116,10 +119,13 @@
    * @Return:
    *   Always 0.  Needed for the interface only.
    */
-  static int
-  BBox_Line_To( FT_Vector*  to,
-                TBBox_Rec*  user )
+  FT_CALLBACK_DEF( int )
+  BBox_Line_To( const FT_Vector*  to,
+                void*             user_ )
   {
+    TBBox_Rec*  user = (TBBox_Rec*)user_;
+
+
     user->last = *to;
 
     return 0;
@@ -205,11 +211,14 @@
    *   In the case of a non-monotonous arc, we compute directly the
    *   extremum coordinates, as it is sufficiently fast.
    */
-  static int
-  BBox_Conic_To( FT_Vector*  control,
-                 FT_Vector*  to,
-                 TBBox_Rec*  user )
+  FT_CALLBACK_DEF( int )
+  BBox_Conic_To( const FT_Vector*  control,
+                 const FT_Vector*  to,
+                 void*             user_ )
   {
+    TBBox_Rec*  user = (TBBox_Rec*)user_;
+
+
     /* in case `to' is implicit and not included in bbox yet */
     FT_UPDATE_BBOX( to, user->bbox );
 
@@ -410,12 +419,15 @@
    *   In the case of a non-monotonous arc, we don't compute directly
    *   extremum coordinates, we subdivide instead.
    */
-  static int
-  BBox_Cubic_To( FT_Vector*  control1,
-                 FT_Vector*  control2,
-                 FT_Vector*  to,
-                 TBBox_Rec*  user )
+  FT_CALLBACK_DEF( int )
+  BBox_Cubic_To( const FT_Vector*  control1,
+                 const FT_Vector*  control2,
+                 const FT_Vector*  to,
+                 void*             user_ )
   {
+    TBBox_Rec*  user = (TBBox_Rec*)user_;
+
+
     /* We don't need to check `to' since it is always an on-point,    */
     /* thus within the bbox.  Only segments with an off-point outside */
     /* the bbox can possibly reach new extreme values.                */
diff --git a/src/base/ftobjs.c b/src/base/ftobjs.c
index ad6ef0ae1..b7e89540e 100644
--- a/src/base/ftobjs.c
+++ b/src/base/ftobjs.c
@@ -1245,9 +1245,13 @@
   /* destructor for sizes list */
   static void
   destroy_size( FT_Memory  memory,
-                FT_Size    size,
-                FT_Driver  driver )
+                void*      size_,
+                void*      driver_ )
   {
+    FT_Size    size   = (FT_Size)size_;
+    FT_Driver  driver = (FT_Driver)driver_;
+
+
     /* finalize client-specific data */
     if ( size->generic.finalizer )
       size->generic.finalizer( size );
@@ -1293,10 +1297,12 @@
   /* destructor for faces list */
   static void
   destroy_face( FT_Memory  memory,
-                FT_Face    face,
-                FT_Driver  driver )
+                void*      face_,
+                void*      driver_ )
   {
-    FT_Driver_Class  clazz = driver->clazz;
+    FT_Face          face   = (FT_Face)face_;
+    FT_Driver        driver = (FT_Driver)driver_;
+    FT_Driver_Class  clazz  = driver->clazz;
 
 
     /* discard auto-hinting data */
@@ -1310,7 +1316,7 @@
 
     /* discard all sizes for this face */
     FT_List_Finalize( &face->sizes_list,
-                      (FT_List_Destructor)destroy_size,
+                      destroy_size,
                       memory,
                       driver );
     face->size = NULL;
@@ -1346,7 +1352,7 @@
   Destroy_Driver( FT_Driver  driver )
   {
     FT_List_Finalize( &driver->faces_list,
-                      (FT_List_Destructor)destroy_face,
+                      destroy_face,
                       driver->root.memory,
                       driver );
   }