diff --git a/src/hotspot/share/opto/block.hpp b/src/hotspot/share/opto/block.hpp
index 2a08328b95c..e48b50b06ae 100644
--- a/src/hotspot/share/opto/block.hpp
+++ b/src/hotspot/share/opto/block.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -281,7 +281,7 @@ public:
       _succs(a),
       _num_succs(0),
       _pre_order(0),
-      _idom(0),
+      _idom(nullptr),
       _loop(nullptr),
       _reg_pressure(0),
       _ihrp_index(1),
diff --git a/src/hotspot/share/opto/cfgnode.hpp b/src/hotspot/share/opto/cfgnode.hpp
index 32ac8c0162f..18d7577d9e6 100644
--- a/src/hotspot/share/opto/cfgnode.hpp
+++ b/src/hotspot/share/opto/cfgnode.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -238,7 +238,7 @@ public:
   int is_diamond_phi() const;
   bool try_clean_memory_phi(PhaseIterGVN* igvn);
   virtual int Opcode() const;
-  virtual bool pinned() const { return in(0) != 0; }
+  virtual bool pinned() const { return in(0) != nullptr; }
   virtual const TypePtr *adr_type() const { verify_adr_type(true); return _adr_type; }
 
   void  set_inst_mem_id(int inst_mem_id) { _inst_mem_id = inst_mem_id; }
diff --git a/src/hotspot/share/opto/constantTable.hpp b/src/hotspot/share/opto/constantTable.hpp
index f7197783773..74d310ec8d5 100644
--- a/src/hotspot/share/opto/constantTable.hpp
+++ b/src/hotspot/share/opto/constantTable.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -50,7 +50,7 @@ public:
     bool      _can_be_reused;  // true (default) if the value can be shared with other users.
 
   public:
-    Constant() : _type(T_ILLEGAL), _is_array(false), _alignment(-1), _offset(-1), _freq(0.0f), _can_be_reused(true) { _v._value.l = 0; }
+    Constant() : _type(T_ILLEGAL), _is_array(false), _alignment(-1), _offset(-1), _freq(0.0f), _can_be_reused(true) { _v._value.l = nullptr; }
     Constant(BasicType type, jvalue value, float freq = 0.0f, bool can_be_reused = true) :
       _type(type),
       _is_array(false),
diff --git a/src/hotspot/share/opto/machnode.hpp b/src/hotspot/share/opto/machnode.hpp
index 6dbaa8a1396..4d7b9c62aaa 100644
--- a/src/hotspot/share/opto/machnode.hpp
+++ b/src/hotspot/share/opto/machnode.hpp
@@ -1084,7 +1084,7 @@ public:
 
   uint _block_num;
 
-  labelOper() : _label(0), _block_num(0) {}
+  labelOper() : _label(nullptr), _block_num(0) {}
 
   labelOper(Label* label, uint block_num) : _label(label), _block_num(block_num) {}