diff --git a/libc/include/unistd.h b/libc/include/unistd.h
index aaa8f22..e360421 100644
--- a/libc/include/unistd.h
+++ b/libc/include/unistd.h
@@ -313,7 +313,9 @@
 int getdomainname(char* __buf, size_t __buf_size) __INTRODUCED_IN(26);
 int setdomainname(const char* __name, size_t __n) __INTRODUCED_IN(26);
 
+#if __ANDROID_API__ >= 28
 void swab(const void* __src, void* __dst, ssize_t __byte_count) __INTRODUCED_IN(28);
+#endif
 
 #if defined(__BIONIC_INCLUDE_FORTIFY_HEADERS)
 #define _UNISTD_H_
@@ -322,3 +324,5 @@
 #endif
 
 __END_DECLS
+
+#include <android/legacy_unistd_inlines.h>