diff --git a/src/alloy/compiler/compiler.cc b/src/alloy/compiler/compiler.cc
index 2ad7ca527..b74ada3cf 100644
--- a/src/alloy/compiler/compiler.cc
+++ b/src/alloy/compiler/compiler.cc
@@ -33,7 +33,8 @@ int Compiler::Compile(HIRBuilder* builder) {
 
   // TODO(benvanik): sophisticated stuff. Run passes in parallel, run until they
   //                 stop changing things, etc.
-  for (auto& pass : passes_) {
+  for (size_t i = 0; i < passes_.size(); ++i) {
+    auto& pass = passes_[i];
     scratch_arena_.Reset();
     if (pass->Run(builder)) {
       return 1;
diff --git a/src/alloy/compiler/passes/control_flow_analysis_pass.cc b/src/alloy/compiler/passes/control_flow_analysis_pass.cc
index 312fa3441..85b2bcfe4 100644
--- a/src/alloy/compiler/passes/control_flow_analysis_pass.cc
+++ b/src/alloy/compiler/passes/control_flow_analysis_pass.cc
@@ -30,10 +30,18 @@ ControlFlowAnalysisPass::~ControlFlowAnalysisPass() {}
 int ControlFlowAnalysisPass::Run(HIRBuilder* builder) {
   SCOPE_profile_cpu_f("alloy");
 
-  // TODO(benvanik): reset edges for all blocks? Needed to be re-runnable.
+  // Reset edges for all blocks. Needed to be re-runnable.
+  // Note that this wastes a bunch of arena memory, so we shouldn't
+  // re-run too often.
+  auto block = builder->first_block();
+  while (block) {
+    block->incoming_edge_head = nullptr;
+    block->outgoing_edge_head = nullptr;
+    block = block->next;
+  }
 
   // Add edges.
-  auto block = builder->first_block();
+  block = builder->first_block();
   while (block) {
     auto instr = block->instr_tail;
     while (instr) {