diff --git a/apps/theming/lib/IconBuilder.php b/apps/theming/lib/IconBuilder.php
index 775731799d82d..d21781e3508d9 100644
--- a/apps/theming/lib/IconBuilder.php
+++ b/apps/theming/lib/IconBuilder.php
@@ -187,7 +187,7 @@ public function renderAppIcon($app, $size) {
 			$finalIconFile->newImage($size, $size, new ImagickPixel('transparent'));
 			$draw = new ImagickDraw();
 			$draw->setFillColor($color);
-			$draw->roundRectangle(0, 0, $size - 1, $size - 1, $cornerRadius, $cornerRadius);
+			$draw->roundRectangle(0, 0, $size, $size, $cornerRadius, $cornerRadius);
 			$finalIconFile->drawImage($draw);
 			$draw->destroy();
 			// overlay icon
diff --git a/apps/theming/tests/IconBuilderTest.php b/apps/theming/tests/IconBuilderTest.php
index 3bfa4ee050c5c..feb447ab517f5 100644
--- a/apps/theming/tests/IconBuilderTest.php
+++ b/apps/theming/tests/IconBuilderTest.php
@@ -320,7 +320,7 @@ private function generateTestIcon(string $file, string $format, int $size, strin
 		$finalIconFile->newImage($size, $size, new \ImagickPixel('transparent'));
 		$draw = new \ImagickDraw();
 		$draw->setFillColor($color);
-		$draw->roundRectangle(0, 0, $size - 1, $size - 1, $cornerRadius, $cornerRadius);
+		$draw->roundRectangle(0, 0, $size, $size, $cornerRadius, $cornerRadius);
 		$finalIconFile->drawImage($draw);
 		$draw->destroy();
 		$finalIconFile->setImageVirtualPixelMethod(\Imagick::VIRTUALPIXELMETHOD_TRANSPARENT);