diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
index e0faf8501bf..520cbee7c1a 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
@@ -3472,6 +3472,11 @@ Instruction::isActionEqual(const Instruction *that) const
    } else
    if (this->asFlow()) {
       return false;
+   } else
+   if (this->op == OP_PHI && this->bb != that->bb) {
+      /* TODO: we could probably be a bit smarter here by following the
+       * control flow, but honestly, it is quite painful to check */
+      return false;
    } else {
       if (this->ipa != that->ipa ||
           this->lanes != that->lanes ||
@@ -3568,6 +3573,7 @@ GlobalCSE::visit(BasicBlock *bb)
             break;
       }
       if (!phi->srcExists(s)) {
+         assert(ik->op != OP_PHI);
          Instruction *entry = bb->getEntry();
          ik->bb->remove(ik);
          if (!entry || entry->op != OP_JOIN)