diff --git a/.github/workflows/.java-version b/.github/workflows/.java-version
index a45fd52cc5..aabe6ec390 100644
--- a/.github/workflows/.java-version
+++ b/.github/workflows/.java-version
@@ -1 +1 @@
-24
+21
diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index 38cfc5ea54..1fc93fe1d5 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -66,6 +66,8 @@ jobs:
           - macos-15
           - ubuntu-24.04
           - ubuntu-24.04-arm
+          - windows-2025
+          - windows-11-arm
     runs-on: ${{ matrix.platform }}
     steps:
       - uses: actions/checkout@v5
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3f44a27770..69543710be 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## Unreleased
 
+* New: Add JVM support for Windows (x64 and ARM).
 * In-development snapshots are now published to the Central Portal Snapshots repository at https://central.sonatype.com/repository/maven-snapshots/.
 
 
diff --git a/zipline/build.zig b/zipline/build.zig
index 3f97ef4c77..4e0acd62ae 100644
--- a/zipline/build.zig
+++ b/zipline/build.zig
@@ -9,6 +9,8 @@ pub fn build(b: *std.Build) !void {
   try setupTarget(b, &deleteLib.step, .linux, .x86_64, "amd64");
   try setupTarget(b, &deleteLib.step, .macos, .aarch64, "aarch64");
   try setupTarget(b, &deleteLib.step, .macos, .x86_64, "x86_64");
+  try setupTarget(b, &deleteLib.step, .windows, .aarch64, "aarch64");
+  try setupTarget(b, &deleteLib.step, .windows, .x86_64, "amd64");
 }
 
 fn setupTarget(b: *std.Build, step: *std.Build.Step, tag: std.Target.Os.Tag, arch: std.Target.Cpu.Arch, dir: []const u8) !void {
@@ -24,9 +26,9 @@ fn setupTarget(b: *std.Build, step: *std.Build.Step, tag: std.Target.Os.Tag, arc
     .optimize = .ReleaseSmall,
   });
 
-  var version_buf: [11]u8 = undefined;
+  var version_buf: [64]u8 = undefined;
   const version = try readVersionFile(&version_buf);
-  var quoted_version_buf: [12]u8 = undefined;
+  var quoted_version_buf: [64]u8 = undefined;
   const quoted_version = try std.fmt.bufPrint(&quoted_version_buf, "\"{s}\"", .{ version });
   lib.root_module.addCMacro("CONFIG_VERSION", quoted_version);
 
@@ -81,15 +83,11 @@ fn setupTarget(b: *std.Build, step: *std.Build.Step, tag: std.Target.Os.Tag, arc
   step.dependOn(&install.step);
 }
 
-fn readVersionFile(version_buf: []u8) ![]u8 {
-  const version_file = try std.fs.cwd().openFile(
+fn readVersionFile(version_buf: []u8) ![]const u8 {
+  const version = try std.fs.cwd().readFile(
     "native/quickjs/VERSION",
-    .{ },
+    version_buf,
   );
-  defer version_file.close();
 
-  var version_file_reader = std.io.bufferedReader(version_file.reader());
-  var version_file_stream = version_file_reader.reader();
-  const version = try version_file_stream.readUntilDelimiterOrEof(version_buf, '\n');
-  return version.?;
+  return std.mem.trim(u8, version, "\r\n");
 }
diff --git a/zipline/src/jniTest/kotlin/app/cash/zipline/ThrowableSerializerTest.kt b/zipline/src/jniTest/kotlin/app/cash/zipline/ThrowableSerializerTest.kt
index 7661b82eca..1dc7c5ed2c 100644
--- a/zipline/src/jniTest/kotlin/app/cash/zipline/ThrowableSerializerTest.kt
+++ b/zipline/src/jniTest/kotlin/app/cash/zipline/ThrowableSerializerTest.kt
@@ -18,6 +18,7 @@ package app.cash.zipline
 import app.cash.zipline.internal.bridge.ThrowableSerializer
 import assertk.assertThat
 import assertk.assertions.isEqualTo
+import java.util.Locale.US
 import kotlin.coroutines.cancellation.CancellationException
 import kotlin.test.assertEquals
 import kotlinx.serialization.json.Json
@@ -31,6 +32,17 @@ class ThrowableSerializerTest {
       contextual(Throwable::class, ThrowableSerializer)
     }
   }
+  private val newline: String
+  private val newlineEscape: String
+  init {
+    if ("windows" in System.getProperty("os.name").lowercase(US)) {
+      newline = "\r\n"
+      newlineEscape = "\\r\\n"
+    } else {
+      newline = "\n"
+      newlineEscape = "\\n"
+    }
+  }
 
   @Test fun happyPath() {
     val exception = Exception("boom")
@@ -41,7 +53,7 @@ class ThrowableSerializerTest {
     val exceptionJson = """
       |{
       |    "types": [],
-      |    "stacktraceString": "java.lang.Exception: boom\n\tat ThrowableSerializerTest.goBoom(test.kt:5)"
+      |    "stacktraceString": "java.lang.Exception: boom$newlineEscape\tat ThrowableSerializerTest.goBoom(test.kt:5)"
       |}
       """.trimMargin()
 
@@ -53,10 +65,7 @@ class ThrowableSerializerTest {
     val decoded = json.decodeFromString(ThrowableSerializer, exceptionJson)
     assertEquals(ZiplineException::class, decoded::class)
     assertEquals(
-      """
-      |java.lang.Exception: boom
-      |${'\t'}at ThrowableSerializerTest.goBoom(test.kt:5)
-      """.trimMargin(),
+      "java.lang.Exception: boom$newline\tat ThrowableSerializerTest.goBoom(test.kt:5)",
       decoded.message,
     )
   }
diff --git a/zipline/src/jvmMain/kotlin/app/cash/zipline/QuickJsNativeLoader.kt b/zipline/src/jvmMain/kotlin/app/cash/zipline/QuickJsNativeLoader.kt
index dbeea79cb1..17bde4ee9f 100644
--- a/zipline/src/jvmMain/kotlin/app/cash/zipline/QuickJsNativeLoader.kt
+++ b/zipline/src/jvmMain/kotlin/app/cash/zipline/QuickJsNativeLoader.kt
@@ -29,6 +29,8 @@ internal actual fun loadNativeLibrary() {
     "/jni/$osArch/libquickjs.so"
   } else if (osName.contains("mac")) {
     "/jni/$osArch/libquickjs.dylib"
+  } else if (osName.contains("windows")) {
+    "/jni/$osArch/quickjs.dll"
   } else {
     throw IllegalStateException("Unsupported OS: $osName")
   }