diff --git a/Tests/test_image.py b/Tests/test_image.py
index cf60f42af6e..85efd9fcdaa 100644
--- a/Tests/test_image.py
+++ b/Tests/test_image.py
@@ -192,6 +192,10 @@ def test_internals(self):
         assert not im.readonly
 
     @pytest.mark.skipif(is_win32(), reason="Test requires opening tempfile twice")
+    @pytest.mark.skipif(
+        sys.platform == "cygwin",
+        reason="Test requires opening an mmaped file for writing",
+    )
     def test_readonly_save(self, tmp_path):
         temp_file = str(tmp_path / "temp.bmp")
         shutil.copy("Tests/images/rgb32bf-rgba.bmp", temp_file)
diff --git a/setup.py b/setup.py
index 1cd22228bfe..23d91a5f24d 100755
--- a/setup.py
+++ b/setup.py
@@ -898,7 +898,7 @@ def build_extensions(self):
         else:
             self._remove_extension("PIL._webp")
 
-        tk_libs = ["psapi"] if sys.platform == "win32" else []
+        tk_libs = ["psapi"] if sys.platform in ("win32", "cygwin") else []
         self._update_extension("PIL._imagingtk", tk_libs)
 
         build_ext.build_extensions(self)
diff --git a/src/Tk/tkImaging.c b/src/Tk/tkImaging.c
index 1c6c5f34a38..9ae7edff108 100644
--- a/src/Tk/tkImaging.c
+++ b/src/Tk/tkImaging.c
@@ -219,7 +219,7 @@ TkImaging_Init(Tcl_Interp *interp) {
 
 #define TKINTER_FINDER "PIL._tkinter_finder"
 
-#if defined(_WIN32) || defined(__WIN32__) || defined(WIN32)
+#if defined(_WIN32) || defined(__WIN32__) || defined(WIN32) || defined(__CYGWIN__)
 
 /*
  * On Windows, we can't load the tkinter module to get the Tcl or Tk symbols,
diff --git a/src/libImaging/ImPlatform.h b/src/libImaging/ImPlatform.h
index 26b49d6d089..af9996ca98c 100644
--- a/src/libImaging/ImPlatform.h
+++ b/src/libImaging/ImPlatform.h
@@ -25,11 +25,18 @@
 #endif
 #endif
 
-#ifdef _WIN32
+#if defined(_WIN32) || defined(__CYGWIN__)
 
 #define WIN32_LEAN_AND_MEAN
 #include <Windows.h>
 
+#ifdef __CYGWIN__
+#undef _WIN64
+#undef _WIN32
+#undef __WIN32__
+#undef WIN32
+#endif
+
 #else
 /* For System that are not Windows, we'll need to define these. */