diff --git a/BanYaroGo/API/APIClient.swift b/BanYaroGo/API/APIClient.swift
index 69942ec..48041b4 100644
--- a/BanYaroGo/API/APIClient.swift
+++ b/BanYaroGo/API/APIClient.swift
@@ -42,7 +42,7 @@ final class APIClient {
         mimeType: String = "image/jpeg"
     ) async throws -> Data {
         let boundary = "Boundary-\(UUID().uuidString)"
-        let url = baseURL.appending(path: path)
+        let url = Self.makeURL(baseURL: baseURL, path: path)
         var req = URLRequest(url: url)
         req.httpMethod = "POST"
         req.setValue("application/json", forHTTPHeaderField: "Accept")
@@ -69,7 +69,7 @@ final class APIClient {
     }
 
     private func perform<T: Decodable>(method: String, path: String, body: Data?) async throws -> T {
-        let url = baseURL.appending(path: path)
+        let url = Self.makeURL(baseURL: baseURL, path: path)
         var req = URLRequest(url: url)
         req.httpMethod = method
         req.setValue("application/json", forHTTPHeaderField: "Accept")
@@ -98,7 +98,7 @@ final class APIClient {
 
     /// Convenience for DELETE with no response body.
     func delete(_ path: String) async throws {
-        let url = baseURL.appending(path: path)
+        let url = Self.makeURL(baseURL: baseURL, path: path)
         var req = URLRequest(url: url)
         req.httpMethod = "DELETE"
         if let token { req.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization") }
@@ -116,7 +116,7 @@ final class APIClient {
     /// Convenience for PATCH with JSON body, decoding the response.
     func patch<T: Decodable, B: Encodable>(_ path: String, body: B) async throws -> T {
         let data = try encoder.encode(body)
-        let url = baseURL.appending(path: path)
+        let url = Self.makeURL(baseURL: baseURL, path: path)
         var req = URLRequest(url: url)
         req.httpMethod = "PATCH"
         req.setValue("application/json", forHTTPHeaderField: "Accept")
@@ -135,6 +135,12 @@ final class APIClient {
         return try decoder.decode(T.self, from: respData)
     }
 
+    /// Constructs a URL by joining baseURL and path as strings — `URL.appending(path:)`
+    /// percent-encodes `?` and breaks query strings.
+    private static func makeURL(baseURL: URL, path: String) -> URL {
+        URL(string: baseURL.absoluteString + path) ?? baseURL
+    }
+
     /// FastAPI returns errors as {"detail": "message"} or {"detail": [{...}]}.
     private static func parseErrorDetail(from data: Data) -> String? {
         if let obj = try? JSONSerialization.jsonObject(with: data) as? [String: Any] {