diff --git a/libc/bionic/pthread_detach.cpp b/libc/bionic/pthread_detach.cpp
index 9f957f4..dcdb7b1 100644
--- a/libc/bionic/pthread_detach.cpp
+++ b/libc/bionic/pthread_detach.cpp
@@ -44,7 +44,7 @@
     }
     switch (old_state) {
       case THREAD_NOT_JOINED: return 0;
-      case THREAD_JOINED:     return 0;  // Already being joined; silently do nothing, like glibc.
+      case THREAD_JOINED:     return EINVAL;
       case THREAD_DETACHED:   return EINVAL;
       case THREAD_EXITED_NOT_JOINED: break;  // Call pthread_join out of scope of pthread_accessor.
     }
diff --git a/tests/pthread_test.cpp b/tests/pthread_test.cpp
index de60f28..251a230 100644
--- a/tests/pthread_test.cpp
+++ b/tests/pthread_test.cpp
@@ -271,8 +271,11 @@
 
   sleep(1); // (Give t2 a chance to call pthread_join.)
 
-  // ...a call to pthread_detach on thread 1 will "succeed" (silently fail)...
+#if defined(__BIONIC__)
+  ASSERT_EQ(EINVAL, pthread_detach(t1));
+#else
   ASSERT_EQ(0, pthread_detach(t1));
+#endif
   AssertDetached(t1, false);
 
   spinhelper.UnSpin();