diff --git a/src/node.cc b/src/node.cc
index ae581a39b92552..dc28fb1d653f1c 100644
--- a/src/node.cc
+++ b/src/node.cc
@@ -429,7 +429,7 @@ void ResetSignalHandlers() {
 #endif  // __POSIX__
 }
 
-static std::atomic<uint64_t> init_process_flags = 0;
+static std::atomic<uint32_t> init_process_flags = 0;
 
 static void PlatformInit(ProcessInitializationFlags::Flags flags) {
   // init_process_flags is accessed in ResetStdio(),
diff --git a/src/node.h b/src/node.h
index 0e307ccb33361b..684bfd40f1a099 100644
--- a/src/node.h
+++ b/src/node.h
@@ -228,7 +228,8 @@ class MultiIsolatePlatform;
 class InitializationResultImpl;
 
 namespace ProcessFlags {
-enum Flags : uint64_t {
+// uint32_t is lock-free
+enum Flags : uint32_t {
   kNoFlags = 0,
   // Enable stdio inheritance, which is disabled by default.
   // This flag is also implied by kNoStdioInitialization.