diff --git a/libc/include/stdlib.h b/libc/include/stdlib.h
index 239f186..266aa5e 100644
--- a/libc/include/stdlib.h
+++ b/libc/include/stdlib.h
@@ -106,8 +106,8 @@
 
 #define RAND_MAX 0x7fffffff
 
-/* Work around x86 libvpx build breakage caused by postproc_x86.c. */
-#if defined(__i386__) && defined(rand)
+/* Work around x86/x86-64 libvpx build breakage caused by postproc_x86.c. */
+#if (defined(__i386__) || defined(__x86_64__)) && defined(rand)
 #undef rand
 #define __rand lrand48
 #endif