diff --git a/src/env.cc b/src/env.cc
index cd7203ffda6e7c..7c1511794bd8e3 100644
--- a/src/env.cc
+++ b/src/env.cc
@@ -615,6 +615,7 @@ IsolateData::IsolateData(Isolate* isolate,
 
 IsolateData::~IsolateData() {
   if (cpp_heap_ != nullptr) {
+    v8::Locker locker(isolate_);
     // The CppHeap must be detached before being terminated.
     isolate_->DetachCppHeap();
     cpp_heap_->Terminate();
diff --git a/test/cctest/test_environment.cc b/test/cctest/test_environment.cc
index 14e82cc80ff730..008cda77b650dc 100644
--- a/test/cctest/test_environment.cc
+++ b/test/cctest/test_environment.cc
@@ -438,6 +438,7 @@ TEST_F(EnvironmentTest, InspectorMultipleEmbeddedEnvironments) {
   // This test sets a global variable in the child Environment, and reads it
   // back both through the inspector and inside the child Environment, and
   // makes sure that those correspond to the value that was originally set.
+  v8::Locker locker(isolate_);
   const v8::HandleScope handle_scope(isolate_);
   const Argv argv;
   Env env {handle_scope, argv};
@@ -507,6 +508,7 @@ TEST_F(EnvironmentTest, InspectorMultipleEmbeddedEnvironments) {
     CHECK_NOT_NULL(isolate);
 
     {
+      v8::Locker locker(isolate);
       v8::Isolate::Scope isolate_scope(isolate);
       v8::HandleScope handle_scope(isolate);
 
@@ -630,6 +632,7 @@ TEST_F(NodeZeroIsolateTestFixture, CtrlCWithOnlySafeTerminationTest) {
 
   // Try creating Context + IsolateData + Environment.
   {
+    v8::Locker locker(isolate);
     v8::Isolate::Scope isolate_scope(isolate);
     v8::HandleScope handle_scope(isolate);
 
diff --git a/test/cctest/test_platform.cc b/test/cctest/test_platform.cc
index fdd51da316ace9..037b6b9cffae85 100644
--- a/test/cctest/test_platform.cc
+++ b/test/cctest/test_platform.cc
@@ -78,6 +78,7 @@ TEST_F(NodeZeroIsolateTestFixture, IsolatePlatformDelegateTest) {
 
   // Try creating Context + IsolateData + Environment
   {
+    v8::Locker locker(isolate);
     v8::Isolate::Scope isolate_scope(isolate);
     v8::HandleScope handle_scope(isolate);