diff --git a/Userland/Services/LookupServer/LookupServer.cpp b/Userland/Services/LookupServer/LookupServer.cpp
index 714c26c1b0..747aafeccc 100644
--- a/Userland/Services/LookupServer/LookupServer.cpp
+++ b/Userland/Services/LookupServer/LookupServer.cpp
@@ -126,7 +126,7 @@ void LookupServer::load_etc_hosts()
 
 static String get_hostname()
 {
-    char buffer[HOST_NAME_MAX];
+    char buffer[_POSIX_HOST_NAME_MAX];
     VERIFY(gethostname(buffer, sizeof(buffer)) == 0);
     return buffer;
 }
diff --git a/Userland/Services/LookupServer/MulticastDNS.cpp b/Userland/Services/LookupServer/MulticastDNS.cpp
index 342c611584..b987334ec1 100644
--- a/Userland/Services/LookupServer/MulticastDNS.cpp
+++ b/Userland/Services/LookupServer/MulticastDNS.cpp
@@ -22,7 +22,7 @@ MulticastDNS::MulticastDNS(Object* parent)
     : Core::UDPServer(parent)
     , m_hostname("courage.local")
 {
-    char buffer[HOST_NAME_MAX];
+    char buffer[_POSIX_HOST_NAME_MAX];
     if (gethostname(buffer, sizeof(buffer)) < 0) {
         perror("gethostname");
     } else {