diff --git a/libc/bionic/readlink.cpp b/libc/bionic/readlink.cpp
index a2c5e91..3bb7bc1 100644
--- a/libc/bionic/readlink.cpp
+++ b/libc/bionic/readlink.cpp
@@ -29,6 +29,7 @@
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/types.h>
+#include <unistd.h>
 
 ssize_t readlink(const char* path, char* buf, size_t size) {
   return readlinkat(AT_FDCWD, path, buf, size);