diff --git a/libc/include/sys/linux-unistd.h b/libc/include/sys/linux-unistd.h
index 6bd9ac7..a439e0f 100644
--- a/libc/include/sys/linux-unistd.h
+++ b/libc/include/sys/linux-unistd.h
@@ -53,7 +53,7 @@
 ssize_t          read (int, void*, size_t);
 ssize_t          write (int, const void*, size_t);
 ssize_t          __pread64 (int, void *, size_t, off_t, off_t);
-ssize_t          __pwrite64 (int, void *, size_t, off_t, off_t);
+ssize_t          __pwrite64 (int, const void *, size_t, off_t, off_t);
 int              __open (const char*, int, mode_t);
 int              __openat (int, const char*, int, mode_t);
 int              close (int);
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);
diff --git a/libc/unistd/pwrite.c b/libc/unistd/pwrite.c
index ea080d2..223e1b3 100644
--- a/libc/unistd/pwrite.c
+++ b/libc/unistd/pwrite.c
@@ -28,9 +28,9 @@
 #include <sys/types.h>
 #include <unistd.h>
 
-extern int __pwrite64(int fd, void *buf, size_t nbytes, loff_t offset);
+extern int __pwrite64(int fd, const void *buf, size_t nbytes, loff_t offset);
 
-ssize_t pwrite(int fd, void *buf, size_t nbytes, off_t offset)
+ssize_t pwrite(int fd, const void *buf, size_t nbytes, off_t offset)
 {
     return __pwrite64(fd, buf, nbytes, offset);
 }