diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/authlibinjector/AuthlibInjectorServer.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/authlibinjector/AuthlibInjectorServer.java
index 947724848..5245ffdf5 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/authlibinjector/AuthlibInjectorServer.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/authlibinjector/AuthlibInjectorServer.java
@@ -29,7 +29,6 @@ import java.net.URISyntaxException;
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Optional;
-import java.util.regex.Pattern;
 
 import org.jackhuang.hmcl.auth.yggdrasil.YggdrasilService;
 import org.jackhuang.hmcl.util.io.HttpRequest;
@@ -58,7 +57,7 @@ public class AuthlibInjectorServer implements Observable {
 
     public static AuthlibInjectorServer locateServer(String url) throws IOException {
         try {
-            url = addHttpsIfMissing(url);
+            url = NetworkUtils.addHttpsIfMissing(url);
             HttpURLConnection conn = NetworkUtils.createHttpConnection(url);
             String ali = conn.getHeaderField("x-authlib-injector-api-location");
             if (ali != null) {
@@ -85,18 +84,6 @@ public class AuthlibInjectorServer implements Observable {
         }
     }
 
-    private static String addHttpsIfMissing(String url) throws IOException {
-        if (Pattern.compile("^(?<scheme>[a-zA-Z][a-zA-Z0-9+.-]*)://").matcher(url).find())
-            return url;
-
-        if (url.startsWith("//"))
-            return "https:" + url;
-        else if (url.startsWith("/"))
-            return "https:/" + url;
-        else
-            return "https://" + url;
-    }
-
     private static boolean urlEqualsIgnoreSlash(String a, String b) {
         if (!a.endsWith("/"))
             a += "/";
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/offline/Skin.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/offline/Skin.java
index e30d6293d..94cb934cb 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/offline/Skin.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/auth/offline/Skin.java
@@ -165,7 +165,7 @@ public class Skin {
             case CUSTOM_SKIN_LOADER_API:
                 String realCslApi = type == Type.LITTLE_SKIN
                         ? "https://littleskin.cn/csl"
-                        : StringUtils.removeSuffix(Lang.requireNonNullElse(cslApi, ""), "/");
+                        : NetworkUtils.addHttpsIfMissing(StringUtils.removeSuffix(Lang.requireNonNullElse(cslApi, ""), "/"));
                 return Task.composeAsync(() -> new GetTask(String.format("%s/%s.json", realCslApi, username)))
                         .thenComposeAsync(json -> {
                             SkinJson result = JsonUtils.GSON.fromJson(json, SkinJson.class);
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/io/NetworkUtils.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/io/NetworkUtils.java
index 2cb67bb86..a0af8a962 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/io/NetworkUtils.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/io/NetworkUtils.java
@@ -63,6 +63,16 @@ public final class NetworkUtils {
         return "http".equals(uri.getScheme()) || "https".equals(uri.getScheme());
     }
 
+    public static String addHttpsIfMissing(String url) {
+        if (Pattern.compile("^(?<scheme>[a-zA-Z][a-zA-Z0-9+.-]*)://").matcher(url).find())
+            return url;
+
+        if (url.startsWith("//"))
+            return "https:" + url;
+        else
+            return "https://" + url;
+    }
+
     public static String withQuery(String baseUrl, Map<String, String> params) {
         StringBuilder sb = new StringBuilder(baseUrl);
         boolean first = true;
@@ -126,7 +136,12 @@ public final class NetworkUtils {
     }
 
     public static URLConnection createConnection(URI uri) throws IOException {
-        URLConnection connection = uri.toURL().openConnection();
+        URLConnection connection;
+        try {
+            connection = uri.toURL().openConnection();
+        } catch (IllegalArgumentException | MalformedURLException e) {
+            throw new IOException(e);
+        }
         connection.setConnectTimeout(TIME_OUT);
         connection.setReadTimeout(TIME_OUT);
         if (connection instanceof HttpURLConnection) {