diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index a48bb4df4d..298652e0f9 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -1301,6 +1301,12 @@ bool Genesis::CompileNative(Vector<const char> name, Handle<String> source) {
 #ifdef ENABLE_DEBUGGER_SUPPORT
   isolate->debugger()->set_compiling_natives(true);
 #endif
+  // During genesis, the boilerplate for stack overflow won't work until the
+  // environment has been at least partially initialized. Add a stack check
+  // before entering JS code to catch overflow early.
+  StackLimitCheck check(Isolate::Current());
+  if (check.HasOverflowed()) return false;
+
   bool result = CompileScriptCached(name,
                                     source,
                                     NULL,
diff --git a/src/debug.cc b/src/debug.cc
index 457531fa36..99256ba21a 100644
--- a/src/debug.cc
+++ b/src/debug.cc
@@ -820,6 +820,9 @@ bool Debug::Load() {
           v8::Handle<ObjectTemplate>(),
           NULL);
 
+  // Fail if no context could be created.
+  if (context.is_null()) return false;
+
   // Use the debugger context.
   SaveContext save(isolate_);
   isolate_->set_context(*context);