diff --git a/LibGUI/GEventLoop.cpp b/LibGUI/GEventLoop.cpp
index cc97d9323ae..5731d303872 100644
--- a/LibGUI/GEventLoop.cpp
+++ b/LibGUI/GEventLoop.cpp
@@ -341,6 +341,12 @@ bool GEventLoop::drain_messages_from_server()
         ByteBuffer extra_data;
         if (message.extra_size) {
             extra_data = ByteBuffer::create_uninitialized(message.extra_size);
+            fd_set rfds;
+            FD_ZERO(&rfds);
+            FD_SET(s_event_fd, &rfds);
+            struct timeval timeout { 1, 0 };
+            int rc = select(s_event_fd + 1, &rfds, nullptr, nullptr, &timeout);
+            ASSERT(rc == 1);
             int extra_nread = read(s_event_fd, extra_data.data(), extra_data.size());
             ASSERT(extra_nread == message.extra_size);
         }
diff --git a/Servers/WindowServer/WSEventLoop.cpp b/Servers/WindowServer/WSEventLoop.cpp
index 8a2e0a28aa4..745d88b9e25 100644
--- a/Servers/WindowServer/WSEventLoop.cpp
+++ b/Servers/WindowServer/WSEventLoop.cpp
@@ -309,6 +309,17 @@ void WSEventLoop::drain_client(WSClientConnection& client)
             }
 
             extra_data = ByteBuffer::create_uninitialized(message.extra_size);
+
+            fd_set rfds;
+            FD_ZERO(&rfds);
+            FD_SET(client.fd(), &rfds);
+            struct timeval timeout { 1, 0 };
+            int rc = select(client.fd() + 1, &rfds, nullptr, nullptr, &timeout);
+            if (rc != 1) {
+                dbgprintf("extra_data didn't show up in time\n");
+                return client.did_misbehave();
+            }
+
             int extra_nread = read(client.fd(), extra_data.data(), extra_data.size());
             if (extra_nread != message.extra_size) {
                 dbgprintf("extra_nread(%d) != extra_size(%d)\n", extra_nread, extra_data.size());