diff --git a/src/mesa/main/readpix.c b/src/mesa/main/readpix.c
index 6f401f111dc..5b3c24627e3 100644
--- a/src/mesa/main/readpix.c
+++ b/src/mesa/main/readpix.c
@@ -284,10 +284,14 @@ slow_read_rgba_pixels( struct gl_context *ctx,
    for (j = 0; j < height; j++) {
       if (_mesa_is_integer_format(format)) {
 	 _mesa_unpack_uint_rgba_row(rbFormat, width, map, (GLuint (*)[4]) rgba);
+         _mesa_rebase_rgba_uint(width, (GLuint (*)[4]) rgba,
+                                rb->_BaseFormat);
 	 _mesa_pack_rgba_span_int(ctx, width, (GLuint (*)[4]) rgba, format,
                                   type, dst);
       } else {
 	 _mesa_unpack_rgba_row(rbFormat, width, map, (GLfloat (*)[4]) rgba);
+         _mesa_rebase_rgba_float(width, (GLfloat (*)[4]) rgba,
+                                 rb->_BaseFormat);
 	 _mesa_pack_rgba_span_float(ctx, width, (GLfloat (*)[4]) rgba, format,
                                     type, dst, packing, transferOps);
       }