diff --git a/Cargo.toml b/Cargo.toml
index e4b6747..0318498 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -19,6 +19,7 @@ license = "MIT"
 default = []
 avoid_timestamping = []
 jack = ["jack-sys", "libc"]
+winjack = ["jack"]
 winrt = [
     "windows/Foundation",
     "windows/Foundation_Collections",
@@ -31,7 +32,7 @@ winrt = [
 [dependencies]
 bitflags = "1.2"
 memalloc = "0.1.0"
-jack-sys = { version = "0.2", optional = true }
+jack-sys = { version = "0.2.3", optional = true }
 libc = { version = "0.2.21", optional = true }
 
 [target.'cfg(target_os = "linux")'.dependencies]
diff --git a/azure-pipelines-template.yml b/azure-pipelines-template.yml
index a76af85..59cc9de 100644
--- a/azure-pipelines-template.yml
+++ b/azure-pipelines-template.yml
@@ -18,6 +18,9 @@ jobs:
         stable-winrt:
           rustup_toolchain: stable-${{ parameters.target }}
           features: "winrt"
+        stable-winjack:
+          rustup_toolchain: stable-${{ parameters.target }}
+          features: "winjack"
         ${{ if eq(variables['Build.SourceBranch'], 'refs/heads/master') }}:
           beta-winrt:
             rustup_toolchain: beta-${{ parameters.target }}
@@ -25,6 +28,12 @@ jobs:
           nightly-winrt:
             rustup_toolchain: nightly-${{ parameters.target }}
             features: "winrt"
+          beta-winjack:
+            rustup_toolchain: beta-${{ parameters.target }}
+            features: "winjack"
+          nightly-winjack:
+            rustup_toolchain: nightly-${{ parameters.target }}
+            features: "winjack"
       ${{ if and(not(startsWith(parameters.name, 'Windows')), not(endsWith(parameters.name, 'WASM'))) }}:
         stable-jack:
           rustup_toolchain: stable-${{ parameters.target }}
@@ -69,6 +78,11 @@ jobs:
         set PATH=%PATH%;%USERPROFILE%\.cargo\bin
         echo "##vso[task.setvariable variable=PATH;]%PATH%;%USERPROFILE%\.cargo\bin"
       displayName: Install Rust (Windows)
+    # Jack on Windows only
+    - powershell: |
+        choco install jack
+      displayName: Install Windows Jack dependency
+      condition: eq(variables.features, 'winjack')
   # All platforms
   - script: |
         rustc -Vv
diff --git a/examples/test_forward.rs b/examples/test_forward.rs
index 1ecb142..6cd1f01 100644
--- a/examples/test_forward.rs
+++ b/examples/test_forward.rs
@@ -1,5 +1,9 @@
 extern crate midir;
 
+#[cfg(all(windows, feature = "winjack"))]
+#[link(name = "C:/Program Files/JACK2/lib/libjack64")]
+extern "C" {}
+
 use std::io::{stdin, stdout, Write};
 use std::error::Error;
 
diff --git a/examples/test_list_ports.rs b/examples/test_list_ports.rs
index 4bc4c6b..54c8fbf 100644
--- a/examples/test_list_ports.rs
+++ b/examples/test_list_ports.rs
@@ -1,5 +1,9 @@
 extern crate midir;
 
+#[cfg(all(windows, feature = "winjack"))]
+#[link(name = "C:/Program Files/JACK2/lib/libjack64")]
+extern "C" {}
+
 use std::io::{stdin, stdout, Write};
 use std::error::Error;
 
diff --git a/examples/test_play.rs b/examples/test_play.rs
index d34e87f..c3c388a 100644
--- a/examples/test_play.rs
+++ b/examples/test_play.rs
@@ -1,5 +1,9 @@
 extern crate midir;
 
+#[cfg(all(windows, feature = "winjack"))]
+#[link(name = "C:/Program Files/JACK2/lib/libjack64")]
+extern "C" {}
+
 use std::thread::sleep;
 use std::time::Duration;
 use std::io::{stdin, stdout, Write};
diff --git a/examples/test_read_input.rs b/examples/test_read_input.rs
index 321ccc7..70686f8 100644
--- a/examples/test_read_input.rs
+++ b/examples/test_read_input.rs
@@ -1,5 +1,9 @@
 extern crate midir;
 
+#[cfg(all(windows, feature = "winjack"))]
+#[link(name = "C:/Program Files/JACK2/lib/libjack64")]
+extern "C" {}
+
 use std::io::{stdin, stdout, Write};
 use std::error::Error;
 
diff --git a/examples/test_reuse.rs b/examples/test_reuse.rs
index 79eeaf9..8210a00 100644
--- a/examples/test_reuse.rs
+++ b/examples/test_reuse.rs
@@ -1,5 +1,9 @@
 extern crate midir;
 
+#[cfg(all(windows, feature = "winjack"))]
+#[link(name = "C:/Program Files/JACK2/lib/libjack64")]
+extern "C" {}
+
 use std::thread::sleep;
 use std::time::Duration;
 use std::io::{stdin, stdout, Write};
diff --git a/examples/test_sysex.rs b/examples/test_sysex.rs
index 79149b3..7fe9a7c 100644
--- a/examples/test_sysex.rs
+++ b/examples/test_sysex.rs
@@ -1,5 +1,9 @@
 extern crate midir;
 
+#[cfg(all(windows, feature = "winjack"))]
+#[link(name = "C:/Program Files/JACK2/lib/libjack64")]
+extern "C" {}
+
 fn main() {
     match example::run() {
         Ok(_) => (),
@@ -7,7 +11,7 @@ fn main() {
     }
 }
 
-#[cfg(not(any(windows, target_arch = "wasm32")))] // virtual ports are not supported on Windows nor on Web MIDI
+#[cfg(not(any(all(windows,not(feature = "winjack")), target_arch = "wasm32")))] // virtual ports are not supported on Windows nor on Web MIDI
 mod example {
 
 use std::thread::sleep;
@@ -15,7 +19,7 @@ use std::time::Duration;
 use std::error::Error;
 
 use midir::{MidiInput, MidiOutput, Ignore};
-use midir::os::unix::VirtualInput;
+use midir::ext::VirtualInput;
 
 const LARGE_SYSEX_SIZE: usize = 5572; // This is the maximum that worked for me
 
@@ -73,7 +77,7 @@ pub fn run() -> Result<(), Box<dyn Error>> {
 }
 
  // needed to compile successfully
-#[cfg(any(windows, target_arch = "wasm32"))] mod example {
+#[cfg(any(all(windows, not(feature = "winjack")), target_arch = "wasm32"))] mod example {
     use std::error::Error;
     pub fn run() -> Result<(), Box<dyn Error>> { Ok(()) }
 }
diff --git a/src/backend/jack/wrappers.rs b/src/backend/jack/wrappers.rs
index ef00e2d..69fae2c 100644
--- a/src/backend/jack/wrappers.rs
+++ b/src/backend/jack/wrappers.rs
@@ -4,7 +4,7 @@ use std::{ptr, slice, str};
 use std::ffi::{CStr, CString};
 use std::ops::Index;
 
-use super::libc::{c_void, size_t};
+use super::libc::{c_void, size_t, c_ulong};
 
 use super::jack_sys::{
     jack_get_time,
@@ -83,7 +83,7 @@ impl Client {
     }
     
     pub fn get_midi_ports(&self, flags: PortFlags) -> PortInfos {
-        let ports_ptr = unsafe { jack_get_ports(self.p, ptr::null_mut(), JACK_DEFAULT_MIDI_TYPE.as_ptr() as *const i8, flags.bits() as u64) };
+        let ports_ptr = unsafe { jack_get_ports(self.p, ptr::null_mut(), JACK_DEFAULT_MIDI_TYPE.as_ptr() as *const i8, flags.bits() as c_ulong) };
         let slice = if ports_ptr.is_null() {
             &[]
         } else {
@@ -97,7 +97,7 @@ impl Client {
     
     pub fn register_midi_port(&mut self, name: &str, flags: PortFlags) -> Result<MidiPort, ()> {
         let c_name = CString::new(name).ok().expect("port name must not contain null bytes");
-        let result = unsafe { jack_port_register(self.p, c_name.as_ptr(), JACK_DEFAULT_MIDI_TYPE.as_ptr() as *const i8, flags.bits() as u64, 0) };
+        let result = unsafe { jack_port_register(self.p, c_name.as_ptr(), JACK_DEFAULT_MIDI_TYPE.as_ptr() as *const i8, flags.bits() as c_ulong, 0) };
         if result.is_null() {
             Err(())
         } else {
@@ -247,4 +247,4 @@ impl Drop for Ringbuffer{
     fn drop(&mut self) {
         unsafe { jack_ringbuffer_free(self.p) }
     }
-}
\ No newline at end of file
+}
diff --git a/src/backend/mod.rs b/src/backend/mod.rs
index 2940dae..d23f880 100644
--- a/src/backend/mod.rs
+++ b/src/backend/mod.rs
@@ -3,11 +3,11 @@
 // TODO: improve feature selection (make sure that there is always exactly one implementation, or enable dynamic backend selection)
 // TODO: allow to disable build dependency on ALSA
 
-#[cfg(all(target_os="windows", not(feature = "winrt")))] mod winmm;
-#[cfg(all(target_os="windows", not(feature = "winrt")))] pub use self::winmm::*;
+#[cfg(all(target_os="windows", not(any(feature = "winrt", feature = "winjack"))))] mod winmm;
+#[cfg(all(target_os="windows", not(any(feature = "winrt", feature = "winjack"))))] pub use self::winmm::*;
 
-#[cfg(all(target_os="windows", feature = "winrt"))] mod winrt;
-#[cfg(all(target_os="windows", feature = "winrt"))] pub use self::winrt::*;
+#[cfg(all(target_os="windows", feature = "winrt", not(feature = "winjack")))] mod winrt;
+#[cfg(all(target_os="windows", feature = "winrt", not(feature = "winjack")))] pub use self::winrt::*;
 
 #[cfg(all(target_os="macos", not(feature = "jack")))] mod coremidi;
 #[cfg(all(target_os="macos", not(feature = "jack")))] pub use self::coremidi::*;
@@ -15,8 +15,8 @@
 #[cfg(all(target_os="linux", not(feature = "jack")))] mod alsa;
 #[cfg(all(target_os="linux", not(feature = "jack")))] pub use self::alsa::*;
 
-#[cfg(all(feature = "jack", not(target_os="windows")))] mod jack;
-#[cfg(all(feature = "jack", not(target_os="windows")))] pub use self::jack::*;
+#[cfg(all(feature = "jack", any(unix, feature = "winjack")))] mod jack;
+#[cfg(all(feature = "jack", any(unix, feature = "winjack")))] pub use self::jack::*;
 
 #[cfg(target_arch="wasm32")] mod webmidi;
 #[cfg(target_arch="wasm32")] pub use self::webmidi::*;
diff --git a/src/common.rs b/src/common.rs
index aed696b..f5eb4d7 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -136,8 +136,8 @@ impl MidiIO for MidiInput {
     }
 }
 
-#[cfg(unix)]
-impl<T: Send> ::os::unix::VirtualInput<T> for MidiInput {
+#[cfg(any(unix, feature = "winjack"))]
+impl<T: Send> ::ext::VirtualInput<T> for MidiInput {
     fn create_virtual<F>(
         self, port_name: &str, callback: F, data: T
     ) -> Result<MidiInputConnection<T>, ConnectError<Self>>
@@ -252,8 +252,8 @@ impl MidiIO for MidiOutput {
     }
 }
 
-#[cfg(unix)]
-impl ::os::unix::VirtualOutput for MidiOutput {
+#[cfg(any(unix, feature = "winjack"))]
+impl ::ext::VirtualOutput for MidiOutput {
     fn create_virtual(self, port_name: &str) -> Result<MidiOutputConnection, ConnectError<MidiOutput>> {
         match self.imp.create_virtual(port_name) {
             Ok(imp) => Ok(MidiOutputConnection { imp: imp }),
diff --git a/src/os/unix.rs b/src/ext.rs
similarity index 83%
rename from src/os/unix.rs
rename to src/ext.rs
index 88dcfee..85e8b0f 100644
--- a/src/os/unix.rs
+++ b/src/ext.rs
@@ -1,10 +1,8 @@
 use ::ConnectError;
 use ::{MidiInputConnection, MidiOutputConnection};
 
-// TODO: maybe move to module `virtual` instead of `os::unix`?
-
 /// Trait that is implemented by `MidiInput` on platforms that
-/// support virtual ports (currently every platform but Windows).
+/// support virtual ports (currently every platform but winmm and winrt).
 pub trait VirtualInput<T: Send> where Self: Sized {
     /// Creates a virtual input port. Once it has been created,
     /// other applications can connect to this port and send MIDI
@@ -16,7 +14,7 @@ pub trait VirtualInput<T: Send> where Self: Sized {
 }
 
 /// Trait that is implemented by `MidiOutput` on platforms that
-/// support virtual ports (currently every platform but Windows).
+/// support virtual ports (currently every platform but winmm and winrt).
 pub trait VirtualOutput where Self: Sized {
     /// Creates a virtual output port. Once it has been created,
     /// other applications can connect to this port and will
@@ -24,4 +22,4 @@ pub trait VirtualOutput where Self: Sized {
     fn create_virtual(
         self, port_name: &str
     ) -> Result<MidiOutputConnection, ConnectError<Self>>;
-}
\ No newline at end of file
+}
diff --git a/src/lib.rs b/src/lib.rs
index 93afe94..9da8e58 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,3 +1,6 @@
+#[cfg(all(feature = "winjack", feature = "winrt"))]
+compile_error!("feature \"winjack\" and \"winrt\" cannot be enabled at the same time");
+
 extern crate memalloc;
 
 #[cfg(feature = "jack")]
@@ -57,7 +60,14 @@ impl MidiMessage {
     }
 }
 
-pub mod os; // include platform-specific behaviour
+#[cfg(any(unix, feature = "winjack"))] pub mod ext;
+
+pub mod os {
+    #[cfg(any(unix, feature = "winjack"))]
+    pub mod unix {
+        pub use ext::{VirtualInput, VirtualOutput};
+    }
+}
 
 mod errors;
 pub use errors::*;
@@ -65,4 +75,4 @@ pub use errors::*;
 mod common;
 pub use common::*;
 
-mod backend;
\ No newline at end of file
+mod backend;
diff --git a/src/os/mod.rs b/src/os/mod.rs
deleted file mode 100644
index 70ff75c..0000000
--- a/src/os/mod.rs
+++ /dev/null
@@ -1 +0,0 @@
-#[cfg(unix)] pub mod unix;
\ No newline at end of file
diff --git a/tests/virtual.rs b/tests/virtual.rs
index 5ac5754..6108ff7 100644
--- a/tests/virtual.rs
+++ b/tests/virtual.rs
@@ -1,12 +1,17 @@
 //! This file contains automated tests, but they require virtual ports and therefore can't work on Windows or Web MIDI ...
-#![cfg(not(any(windows, target_arch = "wasm32")))]
+
+#![cfg(not(any(all(windows, not(feature = "winjack")), target_arch = "wasm32")))]
 extern crate midir;
 
+#[cfg(all(windows, feature = "winjack"))]
+#[link(name = "C:/Program Files/JACK2/lib/libjack64")]
+extern "C" {}
+
 use std::thread::sleep;
 use std::time::Duration;
 
 use midir::{MidiInput, MidiOutput, Ignore, MidiOutputPort};
-use midir::os::unix::{VirtualInput, VirtualOutput};
+use midir::ext::{VirtualInput, VirtualOutput};
 
 #[test]
 fn end_to_end() {