diff --git a/runtime-testsuite/resources/org/antlr/v4/test/runtime/descriptors/LexerExec/ReservedWordsEscaping_NULL.txt b/runtime-testsuite/resources/org/antlr/v4/test/runtime/descriptors/LexerExec/ReservedWordsEscaping_NULL.txt
new file mode 100644
index 0000000000..cd09169580
--- /dev/null
+++ b/runtime-testsuite/resources/org/antlr/v4/test/runtime/descriptors/LexerExec/ReservedWordsEscaping_NULL.txt
@@ -0,0 +1,17 @@
+[notes]
+https://github.com/antlr/antlr4/pull/3889
+
+[type]
+Lexer
+
+[grammar]
+lexer grammar L;
+
+NULL : ('N' | 'n')('U' | 'u')('L' | 'l')('L' | 'l') ;
+
+[input]
+NULL
+
+[output]
+[@0,0:3='NULL',<1>,1:0]
+[@1,4:3='<EOF>',<-1>,1:4]
diff --git a/runtime/Cpp/README.md b/runtime/Cpp/README.md
index 622289ba77..fb5b22da4e 100644
--- a/runtime/Cpp/README.md
+++ b/runtime/Cpp/README.md
@@ -35,12 +35,12 @@ The C++ target has been the work of the following people:
 
 ### Build + Usage Notes
 
-The minimum C++ version to compile the ANTLR C++ runtime with is C++11. The supplied projects can built the runtime either as static or dynamic library, as both 32bit and 64bit arch. The macOS project contains a target for iOS and can also be built using cmake (instead of XCode).
+The minimum C++ version to compile the ANTLR C++ runtime with is C++17. The supplied projects can built the runtime either as static or dynamic library, as both 32bit and 64bit arch. The macOS project contains a target for iOS and can also be built using cmake (instead of XCode).
 
 Include the antlr4-runtime.h umbrella header in your target application to get everything needed to use the library.
 
 If you are compiling with cmake, the minimum version required is cmake 2.8.
-By default, the libraries produced by the CMake build target C++11. If you want to target a different C++ standard, you can explicitly pass the standard - e.g. `-DCMAKE_CXX_STANDARD=17`.
+By default, the libraries produced by the CMake build target C++17. If you want to target a different C++ standard, you can explicitly pass the standard - e.g. `-DCMAKE_CXX_STANDARD=17`.
 
 #### Compiling on Windows with Visual Studio using he Visual Studio projects
 Simply open the VS project from the runtime folder (VS 2019+) and build it.
diff --git a/tool/src/org/antlr/v4/codegen/Target.java b/tool/src/org/antlr/v4/codegen/Target.java
index 2d89281030..e109850309 100644
--- a/tool/src/org/antlr/v4/codegen/Target.java
+++ b/tool/src/org/antlr/v4/codegen/Target.java
@@ -126,7 +126,7 @@ protected void genFile(Grammar g, ST outputFileST, String fileName)
 	 *  to a token type in the generated code.
 	 */
 	public String getTokenTypeAsTargetLabel(Grammar g, int ttype) {
-		String name = g.getTokenName(ttype);
+	    String name = this.escapeIfNeeded(g.getTokenName(ttype));
 		// If name is not valid, return the token type instead
 		if ( Grammar.INVALID_TOKEN_NAME.equals(name) ) {
 			return String.valueOf(ttype);
diff --git a/tool/src/org/antlr/v4/codegen/model/Recognizer.java b/tool/src/org/antlr/v4/codegen/model/Recognizer.java
index 8e07c29d2f..732f50fb20 100644
--- a/tool/src/org/antlr/v4/codegen/model/Recognizer.java
+++ b/tool/src/org/antlr/v4/codegen/model/Recognizer.java
@@ -59,7 +59,7 @@ public Recognizer(OutputModelFactory factory) {
 		for (Map.Entry<String, Integer> entry : g.tokenNameToTypeMap.entrySet()) {
 			Integer ttype = entry.getValue();
 			if ( ttype>0 ) {
-				tokens.put(entry.getKey(), ttype);
+			    tokens.put(gen.getTarget().escapeIfNeeded(entry.getKey()), ttype);
 			}
 		}
 
diff --git a/tool/src/org/antlr/v4/codegen/target/CppTarget.java b/tool/src/org/antlr/v4/codegen/target/CppTarget.java
index f8fc4d2702..b45fa91ef9 100644
--- a/tool/src/org/antlr/v4/codegen/target/CppTarget.java
+++ b/tool/src/org/antlr/v4/codegen/target/CppTarget.java
@@ -39,14 +39,14 @@ public class CppTarget extends Target {
 		"double", "dynamic_cast", "else", "enum", "explicit", "export",
 		"extern", "false", "float", "for", "friend", "goto", "if",
 		"inline", "int", "long", "mutable", "namespace", "new",
-		"noexcept", "not", "not_eq", "nullptr", "operator", "or",
+		"noexcept", "not", "not_eq", "nullptr", "NULL", "operator", "or",
 		"or_eq", "private", "protected", "public", "register",
 		"reinterpret_cast", "requires", "return", "short", "signed",
 		"sizeof", "static", "static_assert", "static_cast", "struct",
 		"switch", "template", "this", "thread_local", "throw", "true",
 		"try", "typedef", "typeid", "typename", "union", "unsigned",
 		"using", "virtual", "void", "volatile", "wchar_t", "while",
-		"xor", "xor_eq",
+		"xor", "xor_eq", 
 
 		"rule", "parserRule"
 	));