diff --git a/libmemunreachable/tests/DisableMalloc_test.cpp b/libmemunreachable/tests/DisableMalloc_test.cpp
index ea5c22c..4e6155b 100644
--- a/libmemunreachable/tests/DisableMalloc_test.cpp
+++ b/libmemunreachable/tests/DisableMalloc_test.cpp
@@ -74,7 +74,7 @@
     {
       alarm(100ms);
       ScopedDisableMalloc disable_malloc;
-      char* ptr = new(char);
+      char* ptr = new (std::nothrow)(char);
       ASSERT_NE(ptr, nullptr);
       delete(ptr);
     }
@@ -89,6 +89,8 @@
       alarm(250ms);
       ScopedDisableMalloc disable_malloc;
       delete(ptr);
+      // Force ptr usage or this code gets optimized away by the arm64 compiler.
+      ASSERT_NE(ptr, nullptr);
     }
   }, "");
 }
diff --git a/libmemunreachable/tests/MemUnreachable_test.cpp b/libmemunreachable/tests/MemUnreachable_test.cpp
index 2ae3db8..71da365 100644
--- a/libmemunreachable/tests/MemUnreachable_test.cpp
+++ b/libmemunreachable/tests/MemUnreachable_test.cpp
@@ -23,8 +23,6 @@
 
 #include <memunreachable/memunreachable.h>
 
-void* ptr;
-
 class HiddenPointer {
  public:
   explicit HiddenPointer(size_t size = 256) {
@@ -92,10 +90,12 @@
   }
 }
 
+void* g_ptr;
+
 TEST(MemunreachableTest, global) {
   HiddenPointer hidden_ptr;
 
-  ptr = hidden_ptr.Get();
+  g_ptr = hidden_ptr.Get();
 
   {
     UnreachableMemoryInfo info;
@@ -104,7 +104,7 @@
     ASSERT_EQ(0U, info.leaks.size());
   }
 
-  ptr = NULL;
+  g_ptr = nullptr;
 
   {
     UnreachableMemoryInfo info;
@@ -126,7 +126,7 @@
 TEST(MemunreachableTest, tls) {
   HiddenPointer hidden_ptr;
   pthread_key_t key;
-  pthread_key_create(&key, NULL);
+  pthread_key_create(&key, nullptr);
 
   pthread_setspecific(key, hidden_ptr.Get());