diff --git a/tommath.h b/tommath.h
index 496ce1c..591d67c 100644
--- a/tommath.h
+++ b/tommath.h
@@ -65,7 +65,7 @@ extern "C" {
    typedef unsigned short     mp_word;
 #elif defined(MP_16BIT)
    typedef unsigned short     mp_digit;
-   typedef unsigned long      mp_word;
+   typedef unsigned int       mp_word;
 #elif defined(MP_64BIT)
    /* for GCC only on supported platforms */
 #ifndef CRYPT