diff --git a/src/compiler/nir/nir_opt_constant_folding.c b/src/compiler/nir/nir_opt_constant_folding.c
index 8526e175ce9..1884cf8ddbe 100644
--- a/src/compiler/nir/nir_opt_constant_folding.c
+++ b/src/compiler/nir/nir_opt_constant_folding.c
@@ -75,6 +75,10 @@ should_fold_bcsel(nir_alu_instr *alu)
    if (alu->def.bit_size > 32)
       return false;
 
+   /* Don't fight with nir_lower_bit_size. */
+   if (alu->op == nir_op_u2u8 || alu->op == nir_op_i2i8)
+      return false;
+
    /* Don't fight with nir_lower_load_const_to_scalar. */
    if (nir_op_is_vec_or_mov(alu->op))
       return false;