diff --git a/src/alloy/compiler/passes/finalization_pass.cc b/src/alloy/compiler/passes/finalization_pass.cc
index 3fa3fc1b6..9a430ecc1 100644
--- a/src/alloy/compiler/passes/finalization_pass.cc
+++ b/src/alloy/compiler/passes/finalization_pass.cc
@@ -44,9 +44,9 @@ int FinalizationPass::Run(HIRBuilder* builder) {
     auto label = block->label_head;
     while (label) {
       if (!label->name) {
-        char* name = (char*)arena->Alloc(6 + 4 + 1);
-        xestrcpya(name, 6 + 1, "_label");
-        char* part = _itoa(label->id, name + 6, 10);
+        const size_t label_len = 6 + 4 + 1;
+        char* name = (char*)arena->Alloc(label_len);
+        xesnprintf(name, label_len, "_label%d", label->id);
         label->name = name;
       }
       label = label->next;