diff --git a/tests/_data/formatter/concat.source2.css b/tests/_data/formatter/concat.source2.css
index 0389b6bd3..8d77bf81b 100644
--- a/tests/_data/formatter/concat.source2.css
+++ b/tests/_data/formatter/concat.source2.css
@@ -1,7 +1,7 @@
 @charset "CP949";
 @import url(concat.source3.css);
 @import url(//fonts.googleapis.com/earlyaccess/nanumgothic.css);
-@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+KR&display=swap');
+@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+KR,wght@0,400;0,700&display=swap');
 .wordpress {
 	border-radius: 4px;
 }
diff --git a/tests/_data/formatter/concat.target1.css b/tests/_data/formatter/concat.target1.css
index b772aebf3..a9b73097c 100644
--- a/tests/_data/formatter/concat.target1.css
+++ b/tests/_data/formatter/concat.target1.css
@@ -1,6 +1,6 @@
 @charset "UTF-8";
 @import url("//fonts.googleapis.com/earlyaccess/nanumgothic.css");
-@import url("https://fonts.googleapis.com/css2?family=Noto+Sans+KR&display=swap");
+@import url("https://fonts.googleapis.com/css2?family=Noto+Sans+KR,wght@0,400;0,700&display=swap");
 /* Original file: tests/_data/formatter/concat.source1.css */
 
 .rhymix {
diff --git a/tests/_data/formatter/concat.target2.css b/tests/_data/formatter/concat.target2.css
index 6cf6e2d1c..21f3fa282 100644
--- a/tests/_data/formatter/concat.target2.css
+++ b/tests/_data/formatter/concat.target2.css
@@ -1,6 +1,6 @@
 @charset "UTF-8";
 @import url("//fonts.googleapis.com/earlyaccess/nanumgothic.css");
-@import url("https://fonts.googleapis.com/css2?family=Noto+Sans+KR&display=swap");
+@import url("https://fonts.googleapis.com/css2?family=Noto+Sans+KR,wght@0,400;0,700&display=swap");
 /* Original file: tests/_data/formatter/concat.source1.css */
 
 @media screen and (max-width: 640px) {
diff --git a/tests/_data/formatter/concat.target3.css b/tests/_data/formatter/concat.target3.css
new file mode 100644
index 000000000..7029df3a1
--- /dev/null
+++ b/tests/_data/formatter/concat.target3.css
@@ -0,0 +1,10 @@
+@charset "UTF-8";
+@import url("//fonts.googleapis.com/earlyaccess/nanumgothic.css");
+@import url("https://fonts.googleapis.com/css2?family=Noto+Sans+KR,wght@0,400;0,700&display=swap");
+/* Original file: tests/_output/concat+minify.target1.css */
+
+.rhymix{background:url("../_data/formatter/foo/bar.jpg")}
+
+/* Original file: tests/_output/concat+minify.target2.css */
+
+.imported{background-image:url("../_data/formatter/test.jpg");font-family:sans-serif}.wordpress{border-radius:4px}.xpressengine{margin:320px}
diff --git a/tests/unit/framework/FormatterTest.php b/tests/unit/framework/FormatterTest.php
index 2c3882413..ed1cb6da6 100644
--- a/tests/unit/framework/FormatterTest.php
+++ b/tests/unit/framework/FormatterTest.php
@@ -164,6 +164,25 @@ class FormatterTest extends \Codeception\Test\Unit
 		$this->assertEquals(trim(file_get_contents($real_target2)), trim($test_with_media_query));
 	}
 
+	public function testConcatMinifiedCSS()
+	{
+		$source1 = \RX_BASEDIR . 'tests/_data/formatter/concat.source1.css';
+		$source2 = \RX_BASEDIR . 'tests/_data/formatter/concat.source2.css';
+		$final_target = \RX_BASEDIR . 'tests/_data/formatter/concat.target3.css';
+		$test_target1 = \RX_BASEDIR . 'tests/_output/concat+minify.target1.css';
+		$test_target2 = \RX_BASEDIR . 'tests/_output/concat+minify.target2.css';
+		$test_target3 = \RX_BASEDIR . 'tests/_output/concat+minify.target3.css';
+
+		$this->assertTrue(Rhymix\Framework\Formatter::minifyCSS($source1, $test_target1));
+		$this->assertTrue(Rhymix\Framework\Formatter::minifyCSS($source2, $test_target2));
+
+		$concat_result = Rhymix\Framework\Formatter::concatCSS(array($test_target1, $test_target2), $test_target3);
+		$this->assertEquals(trim(file_get_contents($final_target)), trim($concat_result));
+
+		unlink($test_target1);
+		unlink($test_target2);
+	}
+
 	public function testConcatJS()
 	{
 		$source1 = \RX_BASEDIR . 'tests/_data/formatter/concat.source1.js';