--- a/tests/src/Functional/ToolkitImagemagickTest.php
+++ b/tests/src/Functional/ToolkitImagemagickTest.php
@@ -492,10 +492,14 @@ class ToolkitImagemagickTest extends BrowserTestBase {
       'viet "with double quotes" hình ảnh thử nghiệm.png',
     ];
     foreach ($file_names as $file) {
+      // On Windows, skip filenames with non-allowed characters.
+      if (substr(PHP_OS, 0, 3) === 'WIN' && preg_match('/[:*?"<>|]/', $file)) {
+        continue;
+      }
       $image = $this->imageFactory->get();
       $this->assertTrue($image->createNew(50, 20, 'png'));
       $file_path = $this->testDirectory . '/' . $file;
-      $this->assertTrue($image->save($file_path));
+      $this->assertTrue($image->save($file_path), $file);
       $image_reloaded = $this->imageFactory->get($file_path, 'gd');
       $this->assertTrue($image_reloaded->isValid(), "Image file '$file' loaded successfully.");
     }
@@ -770,7 +774,13 @@ class ToolkitImagemagickTest extends BrowserTestBase {
       $image->getToolkit()->addArgument($argument);
     }
     $image->save($image_uri . '.derived');
-    $this->assertSame("-resize 100x75! -quality 75 -colorspace 'RGB'", $image->getToolkit()->getStringForBinary());
+    if (substr(PHP_OS, 0, 3) === 'WIN') {
+      $expected = "-resize 100x75! -quality 75 -colorspace \"RGB\"";
+    }
+    else {
+      $expected = "-resize 100x75! -quality 75 -colorspace 'RGB'";
+    }
+    $this->assertSame($expected, $image->getToolkit()->getStringForBinary());
   }
 
   /**
@@ -780,9 +790,9 @@ class ToolkitImagemagickTest extends BrowserTestBase {
     $exec_manager = \Drupal::service('imagemagick.exec_manager');
     $output = '';
     $error = '';
-    // @todo differentiate for Windows?
+    $expected = substr(PHP_OS, 0, 3) !== 'WIN' ? 127 : 1;
     $ret = $exec_manager->runOsShell('pinkpanther', '-inspector Clouseau', 'blake', $output, $error);
-    $this->assertEquals(127, $ret, $error);
+    $this->assertEquals($expected, $ret, $error);
   }
 
   /**
@@ -792,12 +802,12 @@ class ToolkitImagemagickTest extends BrowserTestBase {
     $exec_manager = \Drupal::service('imagemagick.exec_manager');
     $output = '';
     $error = '';
+    $expected = substr(PHP_OS, 0, 3) !== 'WIN' ? 143 : 1;
     // Set a short timeout (1 sec.) and run a process that is expected to last
     // longer (10 secs.). Should return a 'terminate' exit code.
     $exec_manager->setTimeout(1);
-    // @todo differentiate for Windows?
     $ret = $exec_manager->runOsShell('sleep', '10', 'sleep', $output, $error);
-    $this->assertEquals(143, $ret, $error);
+    $this->assertEquals($expected, $ret, $error);
   }
 
 }