diff --git a/src/broadcom/compiler/vir_opt_redundant_flags.c b/src/broadcom/compiler/vir_opt_redundant_flags.c
index b61514f6c99..61ebf5dfa24 100644
--- a/src/broadcom/compiler/vir_opt_redundant_flags.c
+++ b/src/broadcom/compiler/vir_opt_redundant_flags.c
@@ -107,6 +107,10 @@ vir_opt_redundant_flags_block(struct v3d_compile *c, struct qblock *block)
                         continue;
                 }
 
+                /* Flags aren't preserved across a thrsw. */
+                if (inst->qpu.sig.thrsw)
+                        last_flags = NULL;
+
                 if (inst->qpu.flags.apf != V3D_QPU_PF_NONE ||
                     inst->qpu.flags.mpf != V3D_QPU_PF_NONE) {
                         if (last_flags &&