diff --git a/.github/workflows/test.yaml b/.github/workflows/test.yaml
index ce70dcf90ba..a585723979d 100644
--- a/.github/workflows/test.yaml
+++ b/.github/workflows/test.yaml
@@ -171,6 +171,16 @@ jobs:
             # select a reactor.
             trial-args: '--reactor=select'
 
+          # Windows, newest Python supported version with gi reactor.
+          # This needs a python version supported by Deluge GTK distribution.
+          - python-version: '3.10'
+            runs-on: 'windows-2022'
+            tox-env: 'alldeps-withcov-winghagi-windows'
+            job-name: 'win-default-tests-gi'
+            # Distributed trial is not yet suported on Windows.
+            # TOOO; set selector to gi once GI support is available.
+            trial-args: '--reactor=select'
+
           # Windows, newest Python supported version with iocp reactor.
           - python-version: '3.12'
             runs-on: 'windows-2022'
@@ -247,7 +257,7 @@ jobs:
 
     # Make sure the matrix is defined in such a way that this is triggered
     # only on Linux.
-    - name: Install GTK system deps
+    - name: Install GTK system deps on Linux
       if: matrix.platform-deps == 'gtk-platform'
       run: |
         # *-dev dependencies are for pygobject
@@ -261,6 +271,19 @@ jobs:
           gir1.2-gtk-3.0 \
           xvfb
 
+    # Make sure the matrix is defined in such a way that this is triggered
+    # only on Linux.
+    - name: Install GTK system deps on windows
+      if: matrix.tox-env == 'alldeps-withcov-winghagi-windows'
+      shell: pwsh
+      run: |
+        $WebClient = New-Object System.Net.WebClient
+        $WebClient.DownloadFile("https://github.com/deluge-torrent/gvsbuild-release/releases/download/latest/gvsbuild-py3.10-vs16-x64.zip","C:\GTK.zip")
+        7z x C:\GTK.zip -oc:\GTK
+        echo "C:\GTK\release\lib" | Out-File -FilePath $env:GITHUB_PATH -Append
+        echo "C:\GTK\release\bin" | Out-File -FilePath $env:GITHUB_PATH -Append
+        echo "C:\GTK\release" | Out-File -FilePath $env:GITHUB_PATH -Append
+
     - name: Test
       run: |
         ${{ matrix.tox-wrapper }} tox ${{ matrix.trial-target }}
diff --git a/src/twisted/internet/_signals.py b/src/twisted/internet/_signals.py
index 18793bfbba2..a1d4fc53e74 100644
--- a/src/twisted/internet/_signals.py
+++ b/src/twisted/internet/_signals.py
@@ -49,9 +49,15 @@
 from twisted.internet.interfaces import IReadDescriptor
 from twisted.python import failure, log, util
 from twisted.python.runtime import platformType
+from . import fdesc
 
 if platformType == "posix":
-    from . import fdesc, process
+    from .process import reapAllProcesses
+else:
+
+    def reapAllProcesses() -> None:
+        "Do nothing on Windows."
+
 
 SignalHandler: TypeAlias = Callable[[int, Optional[FrameType]], None]
 
@@ -232,7 +238,7 @@ def install(self) -> None:
         # This should only happen if someone used spawnProcess
         # before calling reactor.run (and the process also exited
         # already).
-        process.reapAllProcesses()
+        reapAllProcesses()
 
     def uninstall(self) -> None:
         """
@@ -411,7 +417,7 @@ def wakeUp(self):
 if platformType == "posix":
     _Waker = _UnixWaker
 else:
-    # Primarily Windows and Jython.
+    # Windows, and possibly other platforms without signals support
     _Waker = _SocketWaker  # type: ignore[misc,assignment]
 
 
@@ -442,4 +448,4 @@ def doRead(self) -> None:
         method.
         """
         super().doRead()
-        process.reapAllProcesses()
+        reapAllProcesses()
diff --git a/src/twisted/newsfragments/11987.bugfix b/src/twisted/newsfragments/11987.bugfix
new file mode 100644
index 00000000000..516a38c4eb6
--- /dev/null
+++ b/src/twisted/newsfragments/11987.bugfix
@@ -0,0 +1 @@
+gi and gtk reactors now work again on Windows.
diff --git a/tox.ini b/tox.ini
index 9f5e9613c07..0315ce89a11 100644
--- a/tox.ini
+++ b/tox.ini
@@ -120,6 +120,9 @@ commands =
 
     posix: python -c "print('Running on POSIX (no special dependencies)')"
 
+    ; Install based on the the local GTK based on GitHub Actions and Deluge.
+    winghagi: python -m pip install --no-index --find-links="C:\GTK\release\python" PyGObject
+
     ; Run tests without wrapping them using coverage.
     nocov: python -m twisted.trial --temp-directory={envtmpdir}/_trial_temp --reporter={env:TRIAL_REPORTER:verbose} {env:TRIAL_ARGS:-j8} {posargs:twisted}