diff --git a/libc/arch-arm/bionic/crtbegin_so.c b/libc/arch-arm/bionic/crtbegin_so.c
index 57d19bf..36e4b9c 100644
--- a/libc/arch-arm/bionic/crtbegin_so.c
+++ b/libc/arch-arm/bionic/crtbegin_so.c
@@ -34,10 +34,25 @@
   __cxa_finalize(&__dso_handle);
 }
 
+/* CRT_LEGACY_WORKAROUND should only be defined when building
+ * this file as part of the platform's C library.
+ *
+ * The C library already defines a function named 'atexit()'
+ * for backwards compatibility with older NDK-generated binaries.
+ *
+ * For newer ones, 'atexit' is actually embedded in the C
+ * runtime objects that are linked into the final ELF
+ * binary (shared library or executable), and will call
+ * __cxa_atexit() in order to un-register any atexit()
+ * handler when a library is unloaded.
+ *
+ * This function must be global *and* hidden. Only the
+ * code inside the same ELF binary should be able to access it.
+ */
+
 #ifdef CRT_LEGACY_WORKAROUND
 #include "__dso_handle.h"
 #else
-#include "__dso_handle_so.h"
-#endif
-
+#include "__dso_handle_so.c"
 #include "atexit.h"
+#endif