diff --git a/windows/Sources/FabricSandbox/SandboxCommandLine.swift b/windows/Sources/FabricSandbox/SandboxCommandLine.swift
index 6d46bb0..ca7558b 100644
--- a/windows/Sources/FabricSandbox/SandboxCommandLine.swift
+++ b/windows/Sources/FabricSandbox/SandboxCommandLine.swift
@@ -100,6 +100,8 @@ class SandboxCommandLine {
       args[0] = appPath.path()
     }
 
+    var classpathMap: [String: String] = [:]
+
     for i in 0..<args.count {
       if args[i] == "net.fabricmc.sandbox.Main" {
         // Replace the main class with the runtime entrypoint
@@ -107,7 +109,7 @@ class SandboxCommandLine {
       } else if args[i] == "-classpath" || args[i] == "-cp" {
         // Rewrite the classpath to ensure that all of the entries are within the sandbox.
         args[i + 1] = try rewriteClasspath(
-          args[i + 1], dotMinecraftDir: dotMinecraftDir, sandboxRoot: sandboxRoot)
+          args[i + 1], dotMinecraftDir: dotMinecraftDir, sandboxRoot: sandboxRoot, classpathMap: &classpathMap)
       } else if args[i] == "--versionType" {
         // Prefix the version type with "Sandbox", so it is clear that the game is running in a sandbox.
         foundVersionType = true
@@ -175,12 +177,56 @@ class SandboxCommandLine {
     // Remove any javaagent arguments
     args.removeAll { $0.starts(with: "-javaagent") }
 
+    logger.debug("Classpath map: \(classpathMap)")
+
+    for name in ["fabric.gameJarPath", "fabric.gameJarPath.client", "fabric.gameJarPath.server"] {
+      SandboxCommandLine.modifyJvmProp(name: name, args: &args) { value in
+        let classPath = value.split(separator: ";")
+        var newClasspath: [String] = []
+
+        for path in classPath {
+          let file = File(String(path))
+          let newPath = classpathMap[file.path()]
+          if newPath == nil && file.exists() {
+            logger.warning("Failed to find classpath entry for \(path)")
+          }
+
+          newClasspath.append(newPath ?? String(path))
+        }
+
+        return newClasspath.joined(separator: ";")
+      }
+    }
+
+    SandboxCommandLine.modifyJvmProp(name: "fabric.classPathGroups", args: &args) { value in
+      let groups = value.split(separator: ";;")
+      var newGroups: [String] = []
+
+      for group in groups {
+        let classPath = group.split(separator: ";")
+        var newClasspath: [String] = []
+
+        for path in classPath {
+          let file = File(String(path))
+          let newPath = classpathMap[file.path()]
+          if newPath == nil && file.exists() {
+            logger.warning("Failed to find classpath entry for \(path)")
+          }
+          newClasspath.append(newPath ?? String(path))
+        }
+
+        newGroups.append(newClasspath.joined(separator: ";"))
+      }
+
+      return newGroups.joined(separator: ";;")
+    }
+
     // TODO if an args file was used, we should write a new one with the updated args
     return args
   }
 
   // Read the classpath from the arguments and copy the files to the sandbox, returning the new classpath.
-  func rewriteClasspath(_ classPathArgument: String, dotMinecraftDir: File, sandboxRoot: File)
+  func rewriteClasspath(_ classPathArgument: String, dotMinecraftDir: File, sandboxRoot: File, classpathMap: inout [String: String])
     throws -> String
   {
     let classPath = classPathArgument.split(separator: ";")
@@ -213,11 +259,13 @@ class SandboxCommandLine {
         logger.debug("Copying classpath entry to sandbox: \(source.path()) -> \(target.path())")
         try source.copy(to: target)
         newClasspath.append(target.path())
+        classpathMap[source.path()] = target.path()
       } else {
         // The classpath entry is located within the minecraft jar, so will be mounted into the sandbox.
         let relativePath = source.relative(to: dotMinecraftDir)
         let sandboxPath = sandboxRoot.child(relativePath)
         newClasspath.append(sandboxPath.path())
+        classpathMap[source.path()] = sandboxPath.path()
       }
     }
     return newClasspath.joined(separator: ";")
@@ -252,4 +300,16 @@ class SandboxCommandLine {
     try newClasspathFile.writeString(newEntries.map { $0.path() }.joined(separator: ";"))
     return newClasspathFile
   }
+
+  private static func modifyJvmProp(name: String, args: inout [String], _ func: (String) -> String) {
+    let prop = "-D\(name)="
+    for i in 0..<args.count {
+      if args[i].starts(with: prop) {
+        args[i] = prop + `func`(String(args[i].dropFirst(prop.count)))
+        return
+      }
+    }
+
+    logger.debug("Failed to modify JVM property: \(name)")
+  }
 }
diff --git a/windows/Sources/Packager/main.swift b/windows/Sources/Packager/main.swift
index fc9cfc8..d1ad812 100644
--- a/windows/Sources/Packager/main.swift
+++ b/windows/Sources/Packager/main.swift
@@ -47,6 +47,8 @@ func copyDlls(_ packageDir: File, arch: Architecture, redistributables: [String:
     "swiftCore.dll",
     "swiftCRT.dll",
     "swiftSwiftOnoneSupport.dll",
+    "swift_RegexParser.dll",
+    "swift_StringProcessing.dll",
     "BlocksRuntime.dll",
     "vcruntime140.dll",
     "vcruntime140_1.dll",
diff --git a/windows/Tests/CommandLineTests.swift b/windows/Tests/CommandLineTests.swift
index eb5d7c5..6ef3fd4 100644
--- a/windows/Tests/CommandLineTests.swift
+++ b/windows/Tests/CommandLineTests.swift
@@ -107,6 +107,43 @@ struct CommandLineTests {
     }
   }
 
+  @Test func rewriteGameJarPath() throws {
+    let dummmyDotMinecraftDir = try createTempDir(ext: ".minecraft")
+    let dummySandboxRoot = try createTempDir(ext: ".sandbox")
+
+    defer { try! dummmyDotMinecraftDir.delete() }
+    defer { try! dummySandboxRoot.delete() }
+
+    let binDir = dummmyDotMinecraftDir.child("bin")
+    let dummyJar = binDir.child("test.jar")
+    try binDir.createDirectory()
+    try dummyJar.touch()
+
+    let commandLine = try processCommandLine(
+      ["-cp", dummyJar.path(), "-Dfabric.gameJarPath=" + dummyJar.path()], dotMinecraftDir: dummmyDotMinecraftDir,
+      sandboxRoot: dummySandboxRoot)
+    expectContains(commandLine, ["-Dfabric.gameJarPath=" + dummySandboxRoot.child("bin").child("test.jar").path()])
+  }
+
+  @Test func rewriteClasspathGroups() throws {
+    let dummmyDotMinecraftDir = try createTempDir(ext: ".minecraft")
+    let dummySandboxRoot = try createTempDir(ext: ".sandbox")
+
+    defer { try! dummmyDotMinecraftDir.delete() }
+    defer { try! dummySandboxRoot.delete() }
+
+    let binDir = dummmyDotMinecraftDir.child("bin")
+    let dummyJar = binDir.child("test.jar")
+    try binDir.createDirectory()
+    try dummyJar.touch()
+
+    let commandLine = try processCommandLine(
+      ["-cp", dummyJar.path(), "-Dfabric.classPathGroups=" + dummyJar.path() + ";" + dummyJar.path() + ";;test.jar"], dotMinecraftDir: dummmyDotMinecraftDir,
+      sandboxRoot: dummySandboxRoot)
+    let sbPath = dummySandboxRoot.child("bin").child("test.jar").path()
+    expectContains(commandLine, ["-Dfabric.classPathGroups=" + sbPath + ";" + sbPath + ";;test.jar"])
+  }
+
   private func processCommandLine(
     _ args: [String], dotMinecraftDir: File = File("C:/.minecraft"),
     sandboxRoot: File = File("S:"),