diff --git a/enzyme/Enzyme/FunctionUtils.cpp b/enzyme/Enzyme/FunctionUtils.cpp
index 3193a088e215..ab97f02bb66b 100644
--- a/enzyme/Enzyme/FunctionUtils.cpp
+++ b/enzyme/Enzyme/FunctionUtils.cpp
@@ -2606,21 +2606,44 @@ static bool isNot(Value *a, Value *b) {
 
 struct compare_insts {
 public:
+  DominatorTree &DT;
+  LoopInfo &LI;
+  compare_insts(DominatorTree &DT, LoopInfo &LI) : DT(DT), LI(LI) {} 
+  // return true if B appears later than A.
   bool operator()(Instruction * A, Instruction *B) const {
-  if (A->getParent() != B->getParent())
-    return A < B;
-  return A->comesBefore(B);
+  if (A->getParent() == B->getParent()) {
+    return !A->comesBefore(B);
+  }
+  auto AB = A->getParent();
+  auto BB = B->getParent();
+  assert(AB->getParent() == BB->getParent());
+  if (DT.dominates(AB, BB))
+    return false;
+  if (!DT.dominates(BB, AB))
+    return true;
+  for (auto prev = BB->getPrevNode(); prev; prev = prev->getPrevNode()) {
+    if (prev == AB)
+      return true;
+  }
+  return false;
 }
 };
 
 class DominatorOrderSet : public std::set<Instruction*, compare_insts> {
 public:
-  DominatorOrderSet() : std::set<Instruction*, compare_insts>(compare_insts{}) {}
-  DominatorOrderSet(std::set<Instruction*, compare_insts>::iterator begin, std::set<Instruction*, compare_insts>::iterator end) : std::set<Instruction*, compare_insts>(begin, end, compare_insts{}) {}
+  DominatorOrderSet(DominatorTree &DT, LoopInfo &LI) : std::set<Instruction*, compare_insts>(compare_insts(DT, LI)) {}
+  bool contains(Instruction* I) const { return count(I) != 0; }
+  void remove(Instruction* I) { erase(I); }
+  Instruction* pop_back_val() {
+    auto back = end();
+    back--;
+    auto v = *back;
+    erase(back);
+    return v;
+  }
 };
 
-typedef llvm::SetVector<Instruction *, llvm::SmallVector<Instruction *, 1>,
-        DominatorOrderSet> QueueType;
+typedef DominatorOrderSet QueueType;
 
 std::optional<std::string> fixSparse_inner(Instruction *cur, llvm::Function &F,
                                            QueueType &Q,
@@ -2686,6 +2709,12 @@ std::optional<std::string> fixSparse_inner(Instruction *cur, llvm::Function &F,
           operands.insert(I2);
       }
     }
+    if (Q.contains(I)) {
+        Q.remove(I);
+    }
+    for (auto q : Q)
+        llvm::errs() << " -- q: " << *q << "\n";
+    llvm::errs() << "erasing I: " << *I << "\n";
     I->eraseFromParent();
     for (auto op : operands)
       if (op->getNumUses() == 0) {
@@ -2700,6 +2729,7 @@ std::optional<std::string> fixSparse_inner(Instruction *cur, llvm::Function &F,
     if (cur->getNumUses() == 0) {
       for (size_t i = 0; i < cur->getNumOperands(); i++)
         push(cur->getOperand(i));
+      assert(!Q.contains(cur));
       cur->eraseFromParent();
       return "DCE";
     }
@@ -4142,7 +4172,7 @@ std::optional<std::string> fixSparse_inner(Instruction *cur, llvm::Function &F,
       Value *b = cur->getOperand(1 - i);
 
       // fmul (fmul x:constant, y):z, b:constant .
-      if (auto C = dyn_cast<Constant>(b))
+      if (isa<Constant>(b))
       if (auto z = dyn_cast<BinaryOperator>(prelhs)) {
         if (z->getOpcode() == Instruction::FMul) {
           for (int j = 0; j < 2; j++) {
@@ -5509,7 +5539,7 @@ void fixSparseIndices(llvm::Function &F, llvm::FunctionAnalysisManager &FAM,
   auto &LI = FAM.getResult<LoopAnalysis>(F);
   auto &DL = F.getParent()->getDataLayout();
 
-  QueueType Q;
+  QueueType Q(DT, LI);
   {
     llvm::SetVector<BasicBlock *> todoBlocks;
     for (auto b : toDenseBlocks) {
@@ -5530,7 +5560,8 @@ void fixSparseIndices(llvm::Function &F, llvm::FunctionAnalysisManager &FAM,
   // Full simplification
   while (!Q.empty()) {
     auto cur = Q.pop_back_val();
-    QueueType prev(Q.begin(), Q.end());
+    std::set<Instruction*> prev;
+    for (auto v : Q) prev.insert(v);
     llvm::errs() << "\n\n\n\n" << F << "\ncur: " << *cur << "\n";
     auto changed = fixSparse_inner(cur, F, Q, DT, SE, LI, DL);
     (void)changed;
@@ -5538,7 +5569,7 @@ void fixSparseIndices(llvm::Function &F, llvm::FunctionAnalysisManager &FAM,
     llvm::errs() << "changed: " << *changed << "\n";
 
     for (auto I : Q)
-      if (!prev.contains(I))
+      if (!prev.count(I))
         llvm::errs() << " + " << *I << "\n";
     llvm::errs() << F << "\n\n";
     }
diff --git a/enzyme/test/Integration/Sparse/sqrtspring.cpp b/enzyme/test/Integration/Sparse/sqrtspring.cpp
index fdec1f99cdde..40d244704e1f 100644
--- a/enzyme/test/Integration/Sparse/sqrtspring.cpp
+++ b/enzyme/test/Integration/Sparse/sqrtspring.cpp
@@ -7,6 +7,8 @@
 // TODO: if [ %llvmver -ge 12 ]; then %clang++ -fno-exceptions -std=c++11 -O2 %s -S -emit-llvm -o - %newLoadClangEnzyme -mllvm -enzyme-auto-sparsity=1 -S | %lli - ; fi
 // TODO: if [ %llvmver -ge 12 ]; then %clang++ -fno-exceptions -std=c++11 -O3 %s -S -emit-llvm -o - %newLoadClangEnzyme -mllvm -enzyme-auto-sparsity=1 -S | %lli - ; fi
 
+#include <stddef.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <assert.h>
 #include <vector>