diff --git a/libc/arch-arm/bionic/__bionic_clone.S b/libc/arch-arm/bionic/__bionic_clone.S
index 7b76f5e..7cc4db5 100644
--- a/libc/arch-arm/bionic/__bionic_clone.S
+++ b/libc/arch-arm/bionic/__bionic_clone.S
@@ -71,3 +71,4 @@
     ldr    r1, [sp, #-8]
     b      __bionic_clone_entry
 END(__bionic_clone)
+.hidden __bionic_clone
diff --git a/libc/arch-arm64/bionic/__bionic_clone.S b/libc/arch-arm64/bionic/__bionic_clone.S
index 9790291..af91320 100644
--- a/libc/arch-arm64/bionic/__bionic_clone.S
+++ b/libc/arch-arm64/bionic/__bionic_clone.S
@@ -61,3 +61,4 @@
     ldp     x0, x1, [sp, #-16]
     b       __bionic_clone_entry
 END(__bionic_clone)
+.hidden __bionic_clone
diff --git a/libc/arch-mips/bionic/__bionic_clone.S b/libc/arch-mips/bionic/__bionic_clone.S
index 9273134..11d596b 100644
--- a/libc/arch-mips/bionic/__bionic_clone.S
+++ b/libc/arch-mips/bionic/__bionic_clone.S
@@ -66,3 +66,4 @@
 	la	t9,__set_errno
 	j	t9
 END(__bionic_clone)
+.hidden __bionic_clone
diff --git a/libc/arch-mips64/bionic/__bionic_clone.S b/libc/arch-mips64/bionic/__bionic_clone.S
index e1ade30..754861b 100644
--- a/libc/arch-mips64/bionic/__bionic_clone.S
+++ b/libc/arch-mips64/bionic/__bionic_clone.S
@@ -95,3 +95,4 @@
 	PTR_ADDU sp,FRAMESZ
 	j	t9
 	END(__bionic_clone)
+.hidden __bionic_clone
diff --git a/libc/arch-x86/bionic/__bionic_clone.S b/libc/arch-x86/bionic/__bionic_clone.S
index e6ddaaa..bc7f71d 100644
--- a/libc/arch-x86/bionic/__bionic_clone.S
+++ b/libc/arch-x86/bionic/__bionic_clone.S
@@ -51,3 +51,4 @@
         popl    %ebx
         ret
 END(__bionic_clone)
+.hidden __bionic_clone
diff --git a/libc/arch-x86_64/bionic/__bionic_clone.S b/libc/arch-x86_64/bionic/__bionic_clone.S
index cf98d76..c2ebebd 100644
--- a/libc/arch-x86_64/bionic/__bionic_clone.S
+++ b/libc/arch-x86_64/bionic/__bionic_clone.S
@@ -70,3 +70,4 @@
 2:
         ret
 END(__bionic_clone)
+.hidden __bionic_clone
diff --git a/libc/bionic/clone.cpp b/libc/bionic/clone.cpp
index 1d997fe..4ea3c70 100644
--- a/libc/bionic/clone.cpp
+++ b/libc/bionic/clone.cpp
@@ -35,7 +35,7 @@
 extern "C" void __exit(int status);
 
 // Called from the __bionic_clone assembler to call the thread function then exit.
-extern "C" void __bionic_clone_entry(int (*fn)(void*), void* arg) {
+extern "C" __LIBC_HIDDEN__ void __bionic_clone_entry(int (*fn)(void*), void* arg) {
   int status = (*fn)(arg);
   __exit(status);
 }
diff --git a/tests/pthread_test.cpp b/tests/pthread_test.cpp
index 9e7a9bc..6a5e4a6 100644
--- a/tests/pthread_test.cpp
+++ b/tests/pthread_test.cpp
@@ -256,22 +256,6 @@
   ASSERT_EQ(0, pthread_sigmask(SIG_SETMASK, &original_set, NULL));
 }
 
-#if defined(__BIONIC__)
-extern "C" pid_t __bionic_clone(int flags, void* child_stack, pid_t* parent_tid, void* tls, pid_t* child_tid, int (*fn)(void*), void* arg);
-#endif // __BIONIC__
-
-TEST(pthread, __bionic_clone) {
-#if defined(__BIONIC__)
-  // Check that our hand-written clone assembler sets errno correctly on failure.
-  uintptr_t fake_child_stack[16];
-  errno = 0;
-  ASSERT_EQ(-1, __bionic_clone(CLONE_THREAD, &fake_child_stack[16], NULL, NULL, NULL, NULL, NULL));
-  ASSERT_EQ(EINVAL, errno);
-#else // __BIONIC__
-  GTEST_LOG_(INFO) << "This test does nothing.\n";
-#endif // __BIONIC__
-}
-
 TEST(pthread, pthread_setname_np__too_long) {
 #if defined(__BIONIC__) // Not all build servers have a new enough glibc? TODO: remove when they're on gprecise.
   ASSERT_EQ(ERANGE, pthread_setname_np(pthread_self(), "this name is far too long for linux"));
diff --git a/tests/sched_test.cpp b/tests/sched_test.cpp
index 8dba948..7c19962 100644
--- a/tests/sched_test.cpp
+++ b/tests/sched_test.cpp
@@ -51,6 +51,14 @@
 }
 #endif
 
+TEST(sched, clone_errno) {
+  // Check that our hand-written clone assembler sets errno correctly on failure.
+  uintptr_t fake_child_stack[16];
+  errno = 0;
+  ASSERT_EQ(-1, clone(NULL, &fake_child_stack[16], CLONE_THREAD, NULL));
+  ASSERT_EQ(EINVAL, errno);
+}
+
 TEST(sched, cpu_set) {
   cpu_set_t set;