diff --git a/tcg/optimize.c b/tcg/optimize.c
index f69702b26e..1f95da487b 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -1088,8 +1088,9 @@ static bool fold_masks_zosa_int(OptContext *ctx, TCGOp *op,
 
     ti = ts_info(ts);
     ti->z_mask = z_mask;
+    ti->o_mask = o_mask;
 
-    /* Canonicalize s_mask and incorporate data from z_mask. */
+    /* Canonicalize s_mask and incorporate data from [zo]_mask. */
     rep = clz64(~s_mask);
     rep = MAX(rep, clz64(z_mask));
     rep = MAX(rep, clz64(~o_mask));