diff --git a/libc/src/__support/threads/linux/thread.cpp b/libc/src/__support/threads/linux/thread.cpp
--- a/libc/src/__support/threads/linux/thread.cpp
+++ b/libc/src/__support/threads/linux/thread.cpp
@@ -343,18 +343,10 @@
   uint32_t joinable_state = uint32_t(DetachState::JOINABLE);
   if (attrib->detach_state.compare_exchange_strong(
           joinable_state, uint32_t(DetachState::DETACHED))) {
-    return int(DetachType::SIMPLE);
+    return 0;
   }
 
-  // If the thread was already detached, then the detach method should not
-  // be called at all. If the thread is exiting, then we wait for it to exit
-  // and free up resources.
-  // TODO: Should we handle this less destructively? Maybe just return EINVAL?
-  wait();
-
-  cleanup_thread_resources(attrib);
-
-  return int(DetachType::CLEANUP);
+  return EINVAL;
 }
 
 void Thread::wait() {
diff --git a/libc/src/pthread/pthread_detach.cpp b/libc/src/pthread/pthread_detach.cpp
--- a/libc/src/pthread/pthread_detach.cpp
+++ b/libc/src/pthread/pthread_detach.cpp
@@ -20,8 +20,7 @@
 
 LLVM_LIBC_FUNCTION(int, pthread_detach, (pthread_t th)) {
   auto *thread = reinterpret_cast<Thread *>(&th);
-  thread->detach();
-  return 0;
+  return thread->detach();
 }
 
 } // namespace __llvm_libc