diff --git a/libc/include/unistd.h b/libc/include/unistd.h
index d90e737..b801b9d 100644
--- a/libc/include/unistd.h
+++ b/libc/include/unistd.h
@@ -136,7 +136,7 @@
 extern ssize_t read(int, void *, size_t);
 extern ssize_t write(int, const void *, size_t);
 extern ssize_t pread(int, void *, size_t, off_t);
-extern ssize_t pwrite(int, void *, size_t, off_t);
+extern ssize_t pwrite(int, const void *, size_t, off_t);
 
 extern int dup(int);
 extern int dup2(int, int);