diff --git a/tests/arch/ice40/ice40_opt.ys b/tests/arch/ice40/ice40_opt.ys
index 58c33acaa..860e2e211 100644
--- a/tests/arch/ice40/ice40_opt.ys
+++ b/tests/arch/ice40/ice40_opt.ys
@@ -84,3 +84,4 @@ synth_ice40
 select -assert-count 1 t:SB_LUT4
 select -assert-count 1 t:SB_CARRY
 select -assert-count 1 t:SB_CARRY a:keep %i
+select -assert-count 1 t:SB_CARRY c:carry %i