diff --git a/src/Drivers/Gd/Modifiers/TrimModifier.php b/src/Drivers/Gd/Modifiers/TrimModifier.php
index a93e0ea6..10bc64bb 100644
--- a/src/Drivers/Gd/Modifiers/TrimModifier.php
+++ b/src/Drivers/Gd/Modifiers/TrimModifier.php
@@ -57,10 +57,16 @@ public function apply(ImageInterface $image): ImageInterface
      */
     private function trimColor(ImageInterface $image): int
     {
+        // read raw (unblended) pixel values instead of values composited
+        // against a background, so sampled corners match the allocated color
+        imagealphablending($image->core()->native(), false);
+        imagesavealpha($image->core()->native(), true);
+
         // trim color base
         $red = 0;
         $green = 0;
         $blue = 0;
+        $alpha = 0;
 
         // corner coordinates
         $size = $image->size();
@@ -92,13 +98,15 @@ private function trimColor(ImageInterface $image): int
             $red += round(round($rgb['red'] / 51) * 51);
             $green += round(round($rgb['green'] / 51) * 51);
             $blue += round(round($rgb['blue'] / 51) * 51);
+            $alpha += $rgb['alpha'];
         }
 
         $red = (int) round($red / 4);
         $green = (int) round($green / 4);
         $blue = (int) round($blue / 4);
+        $alpha = (int) round($alpha / 4);
 
-        $color = imagecolorallocate($image->core()->native(), $red, $green, $blue);
+        $color = imagecolorallocatealpha($image->core()->native(), $red, $green, $blue, $alpha);
 
         if ($color === false) {
             throw new ModifierException(
diff --git a/tests/Unit/Drivers/Gd/Modifiers/TrimModifierTest.php b/tests/Unit/Drivers/Gd/Modifiers/TrimModifierTest.php
index b5a663d9..8b01578d 100644
--- a/tests/Unit/Drivers/Gd/Modifiers/TrimModifierTest.php
+++ b/tests/Unit/Drivers/Gd/Modifiers/TrimModifierTest.php
@@ -52,4 +52,16 @@ public function testTrimAnimated(): void
         $this->expectException(NotSupportedException::class);
         $image->modify(new TrimModifier());
     }
+
+    public function testTrimTransparentMargin(): void
+    {
+        // circle on transparent background, asymmetric margins
+        // (left 5, top 8, right 12, bottom 15)
+        $image = $this->readTestImage('trim-transparent.png');
+        $this->assertEquals(41, $image->width());
+        $this->assertEquals(47, $image->height());
+        $image->modify(new TrimModifier());
+        $this->assertEquals(25, $image->width());
+        $this->assertEquals(25, $image->height());
+    }
 }
diff --git a/tests/resources/trim-transparent.png b/tests/resources/trim-transparent.png
new file mode 100644
index 00000000..9ad9318b
Binary files /dev/null and b/tests/resources/trim-transparent.png differ