diff --git a/test/cases/at-charset/a.css b/test/cases/at-charset/a.css
new file mode 100644
index 00000000..f503561d
--- /dev/null
+++ b/test/cases/at-charset/a.css
@@ -0,0 +1,11 @@
+@charset "utf-8";
+
+@import "./ae.css";
+@import "./aa.css";
+@import "./ab.css";
+@import "./ac.css";
+@import "./ad.css";
+
+body {
+  background: red;
+}
diff --git a/test/cases/at-charset/aa.css b/test/cases/at-charset/aa.css
new file mode 100644
index 00000000..253ded4b
--- /dev/null
+++ b/test/cases/at-charset/aa.css
@@ -0,0 +1,5 @@
+@charset "utf-8";
+
+.aa {
+  background: green;
+}
diff --git a/test/cases/at-charset/ab.css b/test/cases/at-charset/ab.css
new file mode 100644
index 00000000..56d4d16d
--- /dev/null
+++ b/test/cases/at-charset/ab.css
@@ -0,0 +1,5 @@
+@charset "utf-8";
+
+.ab {
+  background: green;
+}
diff --git a/test/cases/at-charset/ac.css b/test/cases/at-charset/ac.css
new file mode 100644
index 00000000..1cf799c7
--- /dev/null
+++ b/test/cases/at-charset/ac.css
@@ -0,0 +1,5 @@
+@charset "utf-8";
+
+.ac {
+  background: green;
+}
diff --git a/test/cases/at-charset/ad.css b/test/cases/at-charset/ad.css
new file mode 100644
index 00000000..a3af6572
--- /dev/null
+++ b/test/cases/at-charset/ad.css
@@ -0,0 +1,5 @@
+@charset "utf-8";
+
+.ad {
+  background: green;
+}
diff --git a/test/cases/at-charset/ae.css b/test/cases/at-charset/ae.css
new file mode 100644
index 00000000..f001afd5
--- /dev/null
+++ b/test/cases/at-charset/ae.css
@@ -0,0 +1,5 @@
+@charset "utf-8";
+
+.ae {
+  background: green;
+}
diff --git a/test/cases/at-charset/b.css b/test/cases/at-charset/b.css
new file mode 100644
index 00000000..10190b64
--- /dev/null
+++ b/test/cases/at-charset/b.css
@@ -0,0 +1,8 @@
+@charset "utf-8";
+
+@import "./ba.css";
+@import "./bb.css";
+
+body {
+  background: yellow;
+}
diff --git a/test/cases/at-charset/ba.css b/test/cases/at-charset/ba.css
new file mode 100644
index 00000000..b7d79c83
--- /dev/null
+++ b/test/cases/at-charset/ba.css
@@ -0,0 +1,5 @@
+@charset "utf-8";
+
+.ba {
+  background: green;
+}
diff --git a/test/cases/at-charset/bb.css b/test/cases/at-charset/bb.css
new file mode 100644
index 00000000..0fcba139
--- /dev/null
+++ b/test/cases/at-charset/bb.css
@@ -0,0 +1,5 @@
+@charset "utf-8";
+
+.bb {
+  background: green;
+}
diff --git a/test/cases/at-charset/expected/main.css b/test/cases/at-charset/expected/main.css
new file mode 100644
index 00000000..98abe50a
--- /dev/null
+++ b/test/cases/at-charset/expected/main.css
@@ -0,0 +1,54 @@
+@charset "utf-8";
+
+.ae {
+  background: green;
+}
+
+@charset "utf-8";
+
+.aa {
+  background: green;
+}
+
+@charset "utf-8";
+
+.ab {
+  background: green;
+}
+
+@charset "utf-8";
+
+.ac {
+  background: green;
+}
+
+@charset "utf-8";
+
+.ad {
+  background: green;
+}
+
+@charset "utf-8";
+
+body {
+  background: red;
+}
+
+@charset "utf-8";
+
+.ba {
+  background: green;
+}
+
+@charset "utf-8";
+
+.bb {
+  background: green;
+}
+
+@charset "utf-8";
+
+body {
+  background: yellow;
+}
+
diff --git a/test/cases/at-charset/index.js b/test/cases/at-charset/index.js
new file mode 100644
index 00000000..5337afb9
--- /dev/null
+++ b/test/cases/at-charset/index.js
@@ -0,0 +1,2 @@
+import "./a.css";
+import "./b.css";
diff --git a/test/cases/at-charset/webpack.config.js b/test/cases/at-charset/webpack.config.js
new file mode 100644
index 00000000..cf55c08c
--- /dev/null
+++ b/test/cases/at-charset/webpack.config.js
@@ -0,0 +1,18 @@
+import Self from "../../../src";
+
+module.exports = {
+  entry: "./index.js",
+  module: {
+    rules: [
+      {
+        test: /\.css$/,
+        use: [Self.loader, "css-loader"],
+      },
+    ],
+  },
+  plugins: [
+    new Self({
+      filename: "[name].css",
+    }),
+  ],
+};