diff --git a/Source/SocketIO/Engine/SocketEngineSpec.swift b/Source/SocketIO/Engine/SocketEngineSpec.swift
index 3f31c80..4078535 100644
--- a/Source/SocketIO/Engine/SocketEngineSpec.swift
+++ b/Source/SocketIO/Engine/SocketEngineSpec.swift
@@ -156,7 +156,7 @@ extension SocketEngineSpec {
     }
 
     func addHeaders(to req: inout URLRequest, includingCookies additionalCookies: [HTTPCookie]? = nil) {
-        var cookiesToAdd = cookies ?? []
+        var cookiesToAdd: [HTTPCookie] = cookies ?? []
         cookiesToAdd += additionalCookies ?? []
         
         if !cookiesToAdd.isEmpty {