--- a/inst/@galois/conv.m
+++ b/inst/@galois/conv.m
@@ -79,3 +79,7 @@
   endif
 
 endfunction
+
+%%Test input validation
+%!error conv (gf (1, 2), gf (1, 3))
+%!error conv (gf (eye (3), 3), gf (eye (3), 3))