Remove duplicate line
diff --git a/pngrutil.c b/pngrutil.c
index a825f14..2694fa7 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -302,7 +302,6 @@
    if (buffer != NULL && new_size > png_ptr->read_buffer_size)
    {
       png_ptr->read_buffer = NULL;
-      png_ptr->read_buffer = NULL;
       png_ptr->read_buffer_size = 0;
       png_free(png_ptr, buffer);
       buffer = NULL;