diff --git a/tests/stack_protector_test_helper.cpp b/tests/stack_protector_test_helper.cpp
index eddd940..69b3c5d 100644
--- a/tests/stack_protector_test_helper.cpp
+++ b/tests/stack_protector_test_helper.cpp
@@ -15,12 +15,11 @@
  */
 
 // Deliberately overwrite the stack canary.
-__attribute__((noinline)) void modify_stack_protector_test() {
+__attribute__((noinline, optnone)) void modify_stack_protector_test() {
   // We can't use memset here because it's fortified, and we want to test
   // the line of defense *after* that.
-  // Without volatile, the generic x86/x86-64 targets don't write to the stack.
   // We can't make a constant change, since the existing byte might already have
   // had that value.
-  volatile char* p = reinterpret_cast<volatile char*>(&p + 1);
+  char* p = reinterpret_cast<char*>(&p + 1);
   *p = ~*p;
 }