diff --git a/ktor-client/ktor-client-curl/desktop/src/io/ktor/client/engine/curl/CurlProcessor.kt b/ktor-client/ktor-client-curl/desktop/src/io/ktor/client/engine/curl/CurlProcessor.kt
index e72ea57faf..0b0fede325 100644
--- a/ktor-client/ktor-client-curl/desktop/src/io/ktor/client/engine/curl/CurlProcessor.kt
+++ b/ktor-client/ktor-client-curl/desktop/src/io/ktor/client/engine/curl/CurlProcessor.kt
@@ -43,9 +43,8 @@ internal class CurlProcessor(coroutineContext: CoroutineContext) {
     }
 
     suspend fun executeRequest(request: CurlRequestData): CurlSuccess {
-        if (request.isUpgradeRequest && !curlProtocols.contains("ws")) {
-            @Suppress("DEPRECATION")
-            throw CurlRuntimeException("WebSockets are supported in experimental libcurl 7.86 and greater")
+        if (request.isUpgradeRequest && !curlProtocols.contains(request.protocol)) {
+            error("WebSockets are supported in experimental libcurl 7.86 and greater")
         }
 
         val result = CompletableDeferred<CurlSuccess>()
diff --git a/ktor-client/ktor-client-curl/desktop/src/io/ktor/client/engine/curl/internal/CurlRaw.kt b/ktor-client/ktor-client-curl/desktop/src/io/ktor/client/engine/curl/internal/CurlRaw.kt
index 4f0e123343..800d62e9a4 100644
--- a/ktor-client/ktor-client-curl/desktop/src/io/ktor/client/engine/curl/internal/CurlRaw.kt
+++ b/ktor-client/ktor-client-curl/desktop/src/io/ktor/client/engine/curl/internal/CurlRaw.kt
@@ -20,6 +20,7 @@ import kotlin.coroutines.*
 
 @OptIn(ExperimentalForeignApi::class, InternalAPI::class)
 internal suspend fun HttpRequestData.toCurlRequest(config: CurlClientEngineConfig): CurlRequestData = CurlRequestData(
+    protocol = url.protocol.name,
     url = url.toString(),
     method = method.value,
     headers = headersToCurl(),
@@ -36,6 +37,7 @@ internal suspend fun HttpRequestData.toCurlRequest(config: CurlClientEngineConfi
 )
 
 internal class CurlRequestData @OptIn(ExperimentalForeignApi::class) constructor(
+    val protocol: String,
     val url: String,
     val method: String,
     val headers: CPointer<curl_slist>,