diff --git a/Plugins/JavaCompilerPlugin/JavaCompilerPlugin.swift b/Plugins/JavaCompilerPlugin/JavaCompilerPlugin.swift
index e12e13e8..f90150fd 100644
--- a/Plugins/JavaCompilerPlugin/JavaCompilerPlugin.swift
+++ b/Plugins/JavaCompilerPlugin/JavaCompilerPlugin.swift
@@ -30,11 +30,11 @@ struct JavaCompilerBuildToolPlugin: BuildToolPlugin {
 
     // Note: Target doesn't have a directoryURL counterpart to directory,
     // so we cannot eliminate this deprecation warning.
-    let sourceDir = target.directory.string
+    let sourceDir = URL(filePath: target.directory.string)
 
     // The name of the configuration file SwiftJava.config from the target for
     // which we are generating Swift wrappers for Java classes.
-    let configFile = URL(filePath: sourceDir).appending(path: "swift-java.config")
+    let configFile = sourceDir.appending(path: "swift-java.config")
     let config: Configuration?
 
     if let configData = try? Data(contentsOf: configFile) {
@@ -51,13 +51,14 @@ struct JavaCompilerBuildToolPlugin: BuildToolPlugin {
       }
 
       let sourceFilePath = sourceFileURL.path
-      guard sourceFilePath.starts(with: sourceDir) else {
+      let sourceDirPath = sourceDir.path
+      guard sourceFilePath.starts(with: sourceDirPath) else {
         fatalError("Could not get relative path for source file \(sourceFilePath)")
       }
 
       return URL(filePath: context.pluginWorkDirectoryURL.path)
         .appending(path: "Java")
-        .appending(path: String(sourceFilePath.dropFirst(sourceDir.count)))
+        .appending(path: String(sourceFilePath.dropFirst(sourceDirPath.count)))
         .deletingPathExtension()
         .appendingPathExtension("class")
     }
@@ -65,14 +66,19 @@ struct JavaCompilerBuildToolPlugin: BuildToolPlugin {
     let javaHome = URL(filePath: findJavaHome())
     let javaClassFileURL = context.pluginWorkDirectoryURL
       .appending(path: "Java")
+  #if os(Windows)
+    let javac = "javac.exe"
+  #else
+    let javac = "javac"
+  #endif
     return [
       .buildCommand(
         displayName: "Compiling \(javaFiles.count) Java files for target \(sourceModule.name) to \(javaClassFileURL)",
         executable: javaHome
           .appending(path: "bin")
-          .appending(path: "javac"),
-        arguments: javaFiles.map { $0.path(percentEncoded: false) } + [
-          "-d", javaClassFileURL.path(),
+          .appending(path: javac),
+        arguments: javaFiles.map { $0.path } + [
+          "-d", javaClassFileURL.path,
           "-parameters", // keep parameter names, which allows us to emit them in generated Swift decls
         ] + (config?.compilerVersionArgs ?? []),
         inputFiles: javaFiles,
diff --git a/Samples/JavaKitSampleApp/Package.swift b/Samples/JavaKitSampleApp/Package.swift
index 32451e92..881b8d0b 100644
--- a/Samples/JavaKitSampleApp/Package.swift
+++ b/Samples/JavaKitSampleApp/Package.swift
@@ -35,9 +35,8 @@ let javaIncludePath = "\(javaHome)/include"
   let javaPlatformIncludePath = "\(javaIncludePath)/linux"
 #elseif os(macOS)
   let javaPlatformIncludePath = "\(javaIncludePath)/darwin"
-#else
-  // TODO: Handle windows as well
-  #error("Currently only macOS and Linux platforms are supported, this may change in the future.")
+#elseif os(Windows)
+  let javaPlatformIncludePath = "\(javaIncludePath)/win32)"
 #endif
 
 let package = Package(
diff --git a/Sources/SwiftJava/JavaKitVM/JavaVirtualMachine.swift b/Sources/SwiftJava/JavaKitVM/JavaVirtualMachine.swift
index edbddbb7..7443039a 100644
--- a/Sources/SwiftJava/JavaKitVM/JavaVirtualMachine.swift
+++ b/Sources/SwiftJava/JavaKitVM/JavaVirtualMachine.swift
@@ -25,6 +25,14 @@ typealias JNIEnvPointer = UnsafeMutablePointer<JNIEnv?>
 typealias JNIEnvPointer = UnsafeMutableRawPointer
 #endif
 
+extension FileManager {
+#if os(Windows)
+  static let pathSeparator = ";"
+#else
+  static let pathSeparator = ":"
+#endif
+}
+
 public final class JavaVirtualMachine: @unchecked Sendable {
   /// The JNI version that we depend on.
   static let jniVersion = JNI_VERSION_1_6
@@ -81,8 +89,8 @@ public final class JavaVirtualMachine: @unchecked Sendable {
           print("[warning][swift-java][JavaVirtualMachine] Missing classpath element: \(URL(fileURLWithPath: path).absoluteString)") // TODO: stderr
         }
       }
-      let colonSeparatedClassPath = classpath.joined(separator: ":")
-      allVMOptions.append("-Djava.class.path=\(colonSeparatedClassPath)")
+      let pathSeparatedClassPath = classpath.joined(separator: FileManager.pathSeparator)
+      allVMOptions.append("-Djava.class.path=\(pathSeparatedClassPath)")
     }
     allVMOptions.append(contentsOf: vmOptions)
 
@@ -237,7 +245,7 @@ extension JavaVirtualMachine {
     ignoreUnrecognized: Bool = false,
     replace: Bool = false
   ) throws -> JavaVirtualMachine {
-    precondition(!classpath.contains(where: { $0.contains(":") }), "Classpath element must not contain `:`! Split the path into elements! Was: \(classpath)")
+    precondition(!classpath.contains(where: { $0.contains(FileManager.pathSeparator) }), "Classpath element must not contain `\(FileManager.pathSeparator)`! Split the path into elements! Was: \(classpath)")
 
     return try sharedJVM.withLock { (sharedJVMPointer: inout JavaVirtualMachine?) in
       // If we already have a JavaVirtualMachine instance, return it.
diff --git a/Sources/SwiftJava/JavaKitVM/ThreadLocalStorage.swift b/Sources/SwiftJava/JavaKitVM/ThreadLocalStorage.swift
index 7ea0b50a..037e328b 100644
--- a/Sources/SwiftJava/JavaKitVM/ThreadLocalStorage.swift
+++ b/Sources/SwiftJava/JavaKitVM/ThreadLocalStorage.swift
@@ -56,7 +56,7 @@ package struct ThreadLocalStorage: ~Copyable {
     _key = 0
     pthread_key_create(&_key, onThreadExit)
 #elseif canImport(WinSDK)
-    key = FlsAlloc(onThreadExit)
+    _key = FlsAlloc(onThreadExit)
 #endif
   }
 
diff --git a/Sources/_Subprocess/Platforms/Subprocess+Windows.swift b/Sources/_Subprocess/Platforms/Subprocess+Windows.swift
index aaf53ea0..e84d1414 100644
--- a/Sources/_Subprocess/Platforms/Subprocess+Windows.swift
+++ b/Sources/_Subprocess/Platforms/Subprocess+Windows.swift
@@ -1213,8 +1213,7 @@ extension UInt8 {
 extension OutputProtocol {
     internal func output(from data: [UInt8]) throws -> OutputType {
         return try data.withUnsafeBytes {
-            let span = RawSpan(_unsafeBytes: $0)
-            return try self.output(from: span)
+            return try self.output(from: $0)
         }
     }
 }