Fix changeset 2369461 for fixed size matrices
(transplanted from 781a5935cc59ef81d03e6c632485181dc95e01cd)

--HG--
branch : 3.1
extra : transplant_source : x%1AY5%CCY%EF%81%D0%3Elc%24%85%18%1D%C9%5E%01%CD