diff --git a/src/main/java/io/github/zekerzhayard/forgewrapper/installer/Installer.java b/src/main/java/io/github/zekerzhayard/forgewrapper/installer/Installer.java
index 98b9d1a..b2b2f7f 100644
--- a/src/main/java/io/github/zekerzhayard/forgewrapper/installer/Installer.java
+++ b/src/main/java/io/github/zekerzhayard/forgewrapper/installer/Installer.java
@@ -42,7 +42,8 @@ public static Map<String, Object> getData(File librariesDir) {
 
     public static boolean install(File libraryDir, File minecraftJar, File installerJar) throws Throwable {
         ProgressCallback monitor = ProgressCallback.withOutputs(System.out);
-        if (System.getProperty("java.net.preferIPv4Stack") == null) {
+		boolean preferIpv4StackUnset = System.getProperty("java.net.preferIPv4Stack") == null;
+        if (preferIpv4StackUnset) {
             System.setProperty("java.net.preferIPv4Stack", "true");
         }
         String vendor = System.getProperty("java.vendor", "missing vendor");
@@ -55,6 +56,9 @@ public static boolean install(File libraryDir, File minecraftJar, File installer
         // MinecraftForge has removed all old installers since 2024/2/27, but they still exist in NeoForge.
         PostProcessors processors = new PostProcessors(wrapper, true, monitor);
         Method processMethod = PostProcessors.class.getMethod("process", File.class, File.class, File.class, File.class);
+        if (preferIpv4StackUnset) {
+            System.clearProperty("java.net.preferIPv4Stack");
+        }
         if (boolean.class.equals(processMethod.getReturnType())) {
             return (boolean) processMethod.invoke(processors, libraryDir, minecraftJar, libraryDir.getParentFile(), installerJar);
         } else {