diff --git a/pngwrite.c b/pngwrite.c
index c8e98db6b..c5fb4775e 100644
--- a/pngwrite.c
+++ b/pngwrite.c
@@ -939,7 +939,7 @@ png_destroy_write_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
       {
         png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
 
-#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
+#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
         if (png_ptr->num_chunk_list)
         {
            png_free(png_ptr, png_ptr->chunk_list);