diff --git a/libc/private/bionic_mbstate.h b/libc/private/bionic_mbstate.h
index 018b47c..292959a 100644
--- a/libc/private/bionic_mbstate.h
+++ b/libc/private/bionic_mbstate.h
@@ -43,11 +43,31 @@
 #define __MB_IS_ERR(rv) (rv == __MB_ERR_ILLEGAL_SEQUENCE || \
                          rv == __MB_ERR_INCOMPLETE_SEQUENCE)
 
-size_t mbstate_bytes_so_far(const mbstate_t* ps);
-void mbstate_set_byte(mbstate_t* ps, int i, char byte);
-uint8_t mbstate_get_byte(const mbstate_t* ps, int n);
-size_t reset_and_return_illegal(int _errno, mbstate_t* ps);
-size_t reset_and_return(int _return, mbstate_t* ps);
+static inline __wur size_t mbstate_bytes_so_far(const mbstate_t* ps) {
+  return
+      (ps->__seq[2] != 0) ? 3 :
+      (ps->__seq[1] != 0) ? 2 :
+      (ps->__seq[0] != 0) ? 1 : 0;
+}
+
+static inline void mbstate_set_byte(mbstate_t* ps, int i, char byte) {
+  ps->__seq[i] = static_cast<uint8_t>(byte);
+}
+
+static inline __wur uint8_t mbstate_get_byte(const mbstate_t* ps, int n) {
+  return ps->__seq[n];
+}
+
+static inline __wur size_t mbstate_reset_and_return_illegal(int _errno, mbstate_t* ps) {
+  errno = _errno;
+  *(reinterpret_cast<uint32_t*>(ps->__seq)) = 0;
+  return __MB_ERR_ILLEGAL_SEQUENCE;
+}
+
+static inline __wur size_t mbstate_reset_and_return(int _return, mbstate_t* ps) {
+  *(reinterpret_cast<uint32_t*>(ps->__seq)) = 0;
+  return _return;
+}
 
 __END_DECLS