diff --git a/makefile b/makefile
index 882e3950..d51a41b4 100644
--- a/makefile
+++ b/makefile
@@ -38,16 +38,8 @@ endif
 
 UNAME := uname
 UNAME_OS := $(shell $(UNAME) -s | cut -f1 -d_)
-$(info UNAME_OS is $(UNAME_OS))
 ifeq ($(findstring CYGWIN,$(UNAME_OS)), CYGWIN)
 	LIB_DIR:=$(shell cygpath -w $(LIB_DIR))
-else ifeq ($(UNAME_OS),OS/390)
-# The issue is still being investigated. See backlog/issues/1424
-# set -Dfile.encoding=IBM-1047 for JDK21+ zOS for now
-ifeq ($(shell test $(JDK_VERSION) -ge 21; echo $$?),0)
-export IBM_JAVA_OPTIONS="-Dfile.encoding=IBM-1047"
-$(info export IBM_JAVA_OPTIONS="-Dfile.encoding=IBM-1047")
-endif
 endif
 
 export LIB_DIR:=$(subst \,/,$(LIB_DIR))
@@ -90,7 +82,13 @@ compile: buildListGen
 # If AUTO_DETECT is turned on, compile and execute envDetector in build_envInfo.xml.
 #######################################
 envDetect: compileTools
+ifeq ($(UNAME), OS/390)
+ifeq ($(shell test $(JDK_VERSION) -ge 21; echo $$?),0)
+	${TEST_JDK_HOME}$(D)bin$(D)java -Dfile.encoding=IBM-1047 -cp .$(D)bin$(D)TestKitGen.jar org.openj9.envInfo.EnvDetector
+else 
 	${TEST_JDK_HOME}$(D)bin$(D)java -cp .$(D)bin$(D)TestKitGen.jar org.openj9.envInfo.EnvDetector
+endif
+endif
 
 #######################################
 # Generate refined BUILD_LIST.
diff --git a/src/org/testKitGen/MkGen.java b/src/org/testKitGen/MkGen.java
index 15ed029c..8e5b346f 100644
--- a/src/org/testKitGen/MkGen.java
+++ b/src/org/testKitGen/MkGen.java
@@ -14,8 +14,12 @@
 
 package org.testKitGen;
 
+import java.io.FileOutputStream;
 import java.io.FileWriter;
 import java.io.IOException;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -27,6 +31,7 @@ public class MkGen {
 	private List<String> subdirs;
 	private String makeFile;
 	private PlaylistInfo pli;
+	private Writer writer;
 
 	public MkGen(Arguments arg, TestTarget tt, PlaylistInfo pli, String makeFile, List<String> dirList, List<String> subdirs) {
 		this.arg = arg;
@@ -46,7 +51,7 @@ public void start() {
 	}
 
 	private void writeVars() {
-		try (FileWriter f = new FileWriter(makeFile)) {
+		try (Writer f = getWriterObject(makeFile)) {
 			String realtiveRoot = "";
 			int subdirlevel = dirList.size();
 			if (subdirlevel == 0) {
@@ -72,7 +77,7 @@ private void writeVars() {
 		}
 	}
 
-	private void writeSingleTest(List<String> testsInPlaylist, TestInfo testInfo, FileWriter f) throws IOException {
+	private void writeSingleTest(List<String> testsInPlaylist, TestInfo testInfo, Writer f) throws IOException {
 		for (Variation var : testInfo.getVars()) {
 			// Generate make target
 			String testTargetName = var.getSubTestName();
@@ -227,7 +232,7 @@ private void writeSingleTest(List<String> testsInPlaylist, TestInfo testInfo, Fi
 	}
 
 	private void writeTargets() {
-		try (FileWriter f = new FileWriter(makeFile, true)) {
+		try (Writer f = getWriterObject(makeFile)) {
 			if (!pli.getIncludeList().isEmpty()) {
 				for (String include : pli.getIncludeList()) {
 					f.write("-include " + include + "\n\n");
@@ -251,4 +256,18 @@ private void writeTargets() {
 			System.exit(1);
 		}	
 	}
+
+	public Writer getWriterObject(String filetype) {
+		try {
+			if (arg.getSpec().toLowerCase().contains("zos") && (arg.getJdkVersion().equals("21"))) {
+				writer = new OutputStreamWriter(new FileOutputStream(filetype, true), Charset.forName("IBM-1047"));
+			} else {
+				writer = new FileWriter(filetype, true);
+			}
+		} catch(IOException e) {
+			e.printStackTrace();
+			System.exit(1);
+		}
+		return writer;
+	}
 }
\ No newline at end of file
diff --git a/src/org/testKitGen/ModesDictionary.java b/src/org/testKitGen/ModesDictionary.java
index 7ddfa383..9abadb9c 100644
--- a/src/org/testKitGen/ModesDictionary.java
+++ b/src/org/testKitGen/ModesDictionary.java
@@ -98,7 +98,7 @@ private void parseInvalidSpec(Element modes) throws IOException {
 		ArrayList<String> specs = new ArrayList<String>();
 		int lineNum = 0;
 		BufferedReader reader = null;
-		if (arg.getSpec().toLowerCase().contains("zos")) {
+		if (arg.getSpec().toLowerCase().contains("zos") && !(arg.getJdkVersion().equals("21"))) {
 			reader = Files.newBufferedReader(Paths.get(ottawaCsv), Charset.forName("IBM-1047"));
 		} else {
 			reader = Files.newBufferedReader(Paths.get(ottawaCsv));
diff --git a/src/org/testKitGen/UtilsGen.java b/src/org/testKitGen/UtilsGen.java
index 990b4fed..5d9e1fcc 100644
--- a/src/org/testKitGen/UtilsGen.java
+++ b/src/org/testKitGen/UtilsGen.java
@@ -15,13 +15,14 @@
 package org.testKitGen;
 
 import java.io.File;
-import java.io.FileWriter;
 import java.io.IOException;
+import java.io.Writer;
 import java.util.List;
 
 public class UtilsGen {
 	private Arguments arg;
 	private ModesDictionary md;
+	private MkGen mg;
 	private String utilsMk;
 	private String rerunMk;
 	private List<String> ignoreOnRerunList;
@@ -40,7 +41,7 @@ public void generateFiles() {
 	}
 
 	private void generateUtil() {
-		try (FileWriter f = new FileWriter(utilsMk)) {
+		try (Writer f = mg.getWriterObject(utilsMk)) {
 			f.write(Constants.HEADERCOMMENTS);
 			f.write("TOTALCOUNT := " + TestInfo.numOfTests() + "\n");
 			f.write("PLATFORM=\n");
@@ -56,7 +57,7 @@ private void generateUtil() {
 	}
 
 	private void generateRerun() {
-		try (FileWriter f = new FileWriter(rerunMk)) {
+		try (Writer f = mg.getWriterObject(rerunMk)) {
 			f.write(Constants.HEADERCOMMENTS);
 			String ignoreOnRerunStr = String.join(",", ignoreOnRerunList);
 			f.write("IGNORE_ON_RERUN=");