diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_bb.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_bb.cpp
index 51b9225156b..fa8ee072a92 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_bb.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_bb.cpp
@@ -332,6 +332,9 @@ BasicBlock::splitBefore(Instruction *insn, bool attach)
    BasicBlock *bb = new BasicBlock(func);
    assert(!insn || insn->op != OP_PHI);
 
+   bb->joinAt = joinAt;
+   joinAt = NULL;
+
    splitCommon(insn, bb, attach);
    return bb;
 }
diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
index ecd115f9807..9839a0e7bce 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
@@ -1687,6 +1687,7 @@ Converter::insertConvergenceOps(BasicBlock *conv, BasicBlock *fork)
    join->fixed = 1;
    conv->insertHead(join);
 
+   assert(!fork->joinAt);
    fork->joinAt = new_FlowInstruction(func, OP_JOINAT, conv);
    fork->insertBefore(fork->getExit(), fork->joinAt);
 }
diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_lowering_nv50.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_lowering_nv50.cpp
index 2c7f7e326b2..bea293bac99 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_lowering_nv50.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_lowering_nv50.cpp
@@ -871,6 +871,7 @@ NV50LoweringPreSSA::handleTXL(TexInstruction *i)
    BasicBlock *joinBB = i->bb->splitAfter(i);
 
    bld.setPosition(currBB, true);
+   assert(!currBB->joinAt);
    currBB->joinAt = bld.mkFlow(OP_JOINAT, joinBB, CC_ALWAYS, NULL);
 
    for (int l = 0; l <= 3; ++l) {