diff --git a/app/src/main/java/com/m57/hermescontrol/data/ws/HermesWsClient.kt b/app/src/main/java/com/m57/hermescontrol/data/ws/HermesWsClient.kt
index bad4c3e2..1f39d56f 100644
--- a/app/src/main/java/com/m57/hermescontrol/data/ws/HermesWsClient.kt
+++ b/app/src/main/java/com/m57/hermescontrol/data/ws/HermesWsClient.kt
@@ -25,7 +25,7 @@ import kotlinx.coroutines.launch
 import okhttp3.CertificatePinner
 import okhttp3.OkHttpClient
 import okhttp3.Request
-import okhttp3.RequestBody
+import okhttp3.RequestBody.Companion.toRequestBody
 import okhttp3.Response
 import okhttp3.WebSocket
 import okhttp3.WebSocketListener
@@ -166,7 +166,7 @@ object HermesWsClient {
                 Request.Builder()
                     .url("http://${AuthManager.getHost()}:${AuthManager.getPort()}/api/auth/ws-ticket")
                     .header("Cookie", "hermes_session_at=$sessionCookie")
-                    .post(RequestBody.create(null, "{}"))
+                    .post("{}".toRequestBody())
                     .build()
             val response = client.newCall(request).execute()
             if (response.isSuccessful) {
diff --git a/app/src/main/java/com/m57/hermescontrol/ui/authlogin/AuthLoginViewModel.kt b/app/src/main/java/com/m57/hermescontrol/ui/authlogin/AuthLoginViewModel.kt
index da338816..c24106c9 100644
--- a/app/src/main/java/com/m57/hermescontrol/ui/authlogin/AuthLoginViewModel.kt
+++ b/app/src/main/java/com/m57/hermescontrol/ui/authlogin/AuthLoginViewModel.kt
@@ -18,7 +18,7 @@ import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 import okhttp3.OkHttpClient
 import okhttp3.Request
-import okhttp3.RequestBody
+import okhttp3.RequestBody.Companion.toRequestBody
 import java.util.concurrent.TimeUnit
 
 /**
@@ -341,7 +341,7 @@ class AuthLoginViewModel(private val app: Application) : ViewModel() {
                 Request.Builder()
                     .url("$baseUrl/auth/password-login")
                     .header("Content-Type", "application/json")
-                    .post(RequestBody.create(null, jsonBody))
+                    .post(jsonBody.toRequestBody())
                     .build()
             val loginResp = loginClient.newCall(loginReq).execute()
 
@@ -389,7 +389,7 @@ class AuthLoginViewModel(private val app: Application) : ViewModel() {
                 Request.Builder()
                     .url("$baseUrl/api/auth/ws-ticket")
                     .header("Cookie", cookieHeader)
-                    .post(RequestBody.create(null, "{}"))
+                    .post("{}".toRequestBody())
                     .build()
             val ticketResp = ticketClient.newCall(ticketReq).execute()
 
diff --git a/app/src/test/java/com/m57/hermescontrol/data/ws/HermesWsClientTest.kt b/app/src/test/java/com/m57/hermescontrol/data/ws/HermesWsClientTest.kt
index 0e4e8c86..531004a5 100644
--- a/app/src/test/java/com/m57/hermescontrol/data/ws/HermesWsClientTest.kt
+++ b/app/src/test/java/com/m57/hermescontrol/data/ws/HermesWsClientTest.kt
@@ -60,10 +60,11 @@ class HermesWsClientTest {
     fun tearDown() {
         HermesWsClient.disconnect()
         // Wait a bit to allow internal OkHttp coroutines to clean up before shutting down MockWebServer
-        Thread.sleep(100)
+        // Increased from 100ms for OkHttp 5.x — needs more time for the WS close handshake
+        Thread.sleep(500)
         try {
             mockWebServer.shutdown()
-        } catch (e: Exception) {
+        } catch (e: Throwable) {
             e.printStackTrace()
         }
         unmockkAll()
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index a813680c..c3eb2283 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -19,7 +19,7 @@ ksp = "2.3.9"
 nav3Core = "1.0.1"
 lifecycleViewmodelNav3 = "2.10.0"
 leakcanary = "2.14"
-okhttp = "4.12.0"
+okhttp = "5.4.0"
 retrofit = "2.11.0"
 gson = "2.14.0"
 securityCrypto = "1.0.0"