diff --git a/src/cares_wrap.cc b/src/cares_wrap.cc
index 57c02fb32653e5..de05123c22cf4a 100644
--- a/src/cares_wrap.cc
+++ b/src/cares_wrap.cc
@@ -395,7 +395,7 @@ void safe_free_hostent(struct hostent* host) {
       free(host->h_addr_list[idx++]);
     }
     free(host->h_addr_list);
-    host->h_addr_list = 0;
+    host->h_addr_list = nullptr;
   }
 
   if (host->h_aliases != nullptr) {
@@ -404,7 +404,7 @@ void safe_free_hostent(struct hostent* host) {
       free(host->h_aliases[idx++]);
     }
     free(host->h_aliases);
-    host->h_aliases = 0;
+    host->h_aliases = nullptr;
   }
 
   if (host->h_name != nullptr) {
@@ -1914,7 +1914,8 @@ void AfterGetNameInfo(uv_getnameinfo_t* req,
   req_wrap->MakeCallback(env->oncomplete_string(), arraysize(argv), argv);
 }
 
-using ParseIPResult = decltype(static_cast<ares_addr_port_node*>(0)->addr);
+using ParseIPResult =
+    decltype(static_cast<ares_addr_port_node*>(nullptr)->addr);
 
 int ParseIP(const char* ip, ParseIPResult* result = nullptr) {
   ParseIPResult tmp;
diff --git a/src/debug_utils.cc b/src/debug_utils.cc
index 6dac86f002b07d..8e9d9e2bac0e9c 100644
--- a/src/debug_utils.cc
+++ b/src/debug_utils.cc
@@ -66,7 +66,8 @@ class PosixSymbolDebuggingContext final : public NativeSymbolDebuggingContext {
       return ret;
 
     if (info.dli_sname != nullptr) {
-      if (char* demangled = abi::__cxa_demangle(info.dli_sname, 0, 0, 0)) {
+      if (char* demangled =
+              abi::__cxa_demangle(info.dli_sname, nullptr, nullptr, nullptr)) {
         ret.name = demangled;
         free(demangled);
       } else {
diff --git a/src/node.h b/src/node.h
index 72911d7982b72f..44721afa54a812 100644
--- a/src/node.h
+++ b/src/node.h
@@ -562,13 +562,15 @@ extern "C" NODE_EXTERN void node_module_register(void* mod);
 /* Called after the event loop exits but before the VM is disposed.
  * Callbacks are run in reverse order of registration, i.e. newest first.
  */
-NODE_EXTERN void AtExit(void (*cb)(void* arg), void* arg = 0);
+NODE_EXTERN void AtExit(void (*cb)(void* arg), void* arg = nullptr);
 
 /* Registers a callback with the passed-in Environment instance. The callback
  * is called after the event loop exits, but before the VM is disposed.
  * Callbacks are run in reverse order of registration, i.e. newest first.
  */
-NODE_EXTERN void AtExit(Environment* env, void (*cb)(void* arg), void* arg = 0);
+NODE_EXTERN void AtExit(Environment* env,
+                        void (*cb)(void* arg),
+                        void* arg = nullptr);
 
 typedef void (*promise_hook_func) (v8::PromiseHookType type,
                                    v8::Local<v8::Promise> promise,
diff --git a/src/node_crypto.cc b/src/node_crypto.cc
index 228dd0d16da122..b54ce95923d544 100644
--- a/src/node_crypto.cc
+++ b/src/node_crypto.cc
@@ -4827,7 +4827,7 @@ void DiffieHellman::Initialize(Environment* env, Local<Object> target) {
 
 bool DiffieHellman::Init(int primeLength, int g) {
   dh_.reset(DH_new());
-  if (!DH_generate_parameters_ex(dh_.get(), primeLength, g, 0))
+  if (!DH_generate_parameters_ex(dh_.get(), primeLength, g, nullptr))
     return false;
   return VerifyContext();
 }
@@ -4850,8 +4850,10 @@ bool DiffieHellman::Init(const char* p, int p_len, int g) {
 
 bool DiffieHellman::Init(const char* p, int p_len, const char* g, int g_len) {
   dh_.reset(DH_new());
-  BIGNUM* bn_p = BN_bin2bn(reinterpret_cast<const unsigned char*>(p), p_len, 0);
-  BIGNUM* bn_g = BN_bin2bn(reinterpret_cast<const unsigned char*>(g), g_len, 0);
+  BIGNUM* bn_p =
+      BN_bin2bn(reinterpret_cast<const unsigned char*>(p), p_len, nullptr);
+  BIGNUM* bn_g =
+      BN_bin2bn(reinterpret_cast<const unsigned char*>(g), g_len, nullptr);
   if (!DH_set0_pqg(dh_.get(), bn_p, nullptr, bn_g)) {
     BN_free(bn_p);
     BN_free(bn_g);
@@ -5019,7 +5021,7 @@ void DiffieHellman::ComputeSecret(const FunctionCallbackInfo<Value>& args) {
   BignumPointer key(BN_bin2bn(
       reinterpret_cast<unsigned char*>(Buffer::Data(args[0])),
       Buffer::Length(args[0]),
-      0));
+      nullptr));
 
   MallocedBuffer<char> data(DH_size(diffieHellman->dh_.get()));
 
diff --git a/src/util-inl.h b/src/util-inl.h
index 182c50268d3e0a..9f57b635db3357 100644
--- a/src/util-inl.h
+++ b/src/util-inl.h
@@ -143,7 +143,7 @@ typename ListHead<T, M>::Iterator ListHead<T, M>::end() const {
 
 template <typename Inner, typename Outer>
 constexpr uintptr_t OffsetOf(Inner Outer::*field) {
-  return reinterpret_cast<uintptr_t>(&(static_cast<Outer*>(0)->*field));
+  return reinterpret_cast<uintptr_t>(&(static_cast<Outer*>(nullptr)->*field));
 }
 
 template <typename Inner, typename Outer>
diff --git a/src/util.cc b/src/util.cc
index 9f32814a8599ec..81070c239d8ad4 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -48,7 +48,7 @@ static void MakeUtf8String(Isolate* isolate,
   const int flags =
       String::NO_NULL_TERMINATION | String::REPLACE_INVALID_UTF8;
   const int length =
-      string->WriteUtf8(isolate, target->out(), storage, 0, flags);
+      string->WriteUtf8(isolate, target->out(), storage, nullptr, flags);
   target->SetLengthAndZeroTerminate(length);
 }