diff --git a/contrib/sb-gmp/gmp.lisp b/contrib/sb-gmp/gmp.lisp
index 847b59cb3..d0a23a505 100644
--- a/contrib/sb-gmp/gmp.lisp
+++ b/contrib/sb-gmp/gmp.lisp
@@ -97,9 +97,7 @@
 
 ;;; types and initialization
 
-(define-alien-type gmp-limb
-  #-(and win32 64-bit) unsigned-long
-  #+(and win32 64-bit) unsigned-long-long)
+(define-alien-type gmp-limb word)
 
 (deftype ui ()
   #-(and win32 64-bit) 'sb-vm:word
diff --git a/src/code/arena.lisp b/src/code/arena.lisp
index 9e788f46e..a9b362866 100644
--- a/src/code/arena.lisp
+++ b/src/code/arena.lisp
@@ -115,8 +115,7 @@ one or more times, not to exceed MAX-EXTENSIONS times"
   (%primitive delete-arena arena)
   #-x86-64
   (alien-funcall (extern-alien "sbcl_delete_arena"
-                               (function void
-                                         unsigned-long))
+                               (function void word))
                  (get-lisp-obj-address arena))
   ;; It is illegal to access the structure now, since that was in the arena.
   ;; So return an arbitrary success indicator. It might happen that you can accidentally
diff --git a/src/code/target-c-call.lisp b/src/code/target-c-call.lisp
index 12f973397..c24355191 100644
--- a/src/code/target-c-call.lisp
+++ b/src/code/target-c-call.lisp
@@ -34,6 +34,8 @@
 (define-alien-type unsigned-long (unsigned #+win32 32
                                            #-win32 #.sb-vm:n-machine-word-bits))
 (define-alien-type unsigned-long-long (unsigned 64))
+(define-alien-type word (unsigned #.sb-vm:n-machine-word-bits))
+(define-alien-type signed-word (signed #.sb-vm:n-machine-word-bits))
 
 (define-alien-type float single-float)
 (define-alien-type double double-float)
diff --git a/src/cold/exports.lisp b/src/cold/exports.lisp
index 6dc44a55e..4fe4ea653 100644
--- a/src/cold/exports.lisp
+++ b/src/cold/exports.lisp
@@ -1245,6 +1245,7 @@ of SBCL which maintained the CMU-CL-style split into two packages.)")
            "UNLOAD-SHARED-OBJECT"
            "UNSIGNED"
            "UNSIGNED-CHAR" "UNSIGNED-INT" "UNSIGNED-LONG" "UNSIGNED-LONG-LONG" "UNSIGNED-SHORT"
+           "WORD" "SIGNED-WORD"
            "UTF8-STRING"
            "VALUES"
            "VOID"
diff --git a/tests/compiler-2.pure.lisp b/tests/compiler-2.pure.lisp
index 338f1e8ca..fe6dec955 100644
--- a/tests/compiler-2.pure.lisp
+++ b/tests/compiler-2.pure.lisp
@@ -178,11 +178,10 @@
       (sb-sys:with-pinned-objects (packed-int result)
         ;; Now exercise the C unpacker.
         ;; This hack of allocating 4 longs is terrible, but whatever.
-        (let ((unpacker (make-alien (signed #.sb-vm:n-word-bits) 4))
+        (let ((unpacker (make-alien word 4))
               (prev-loc 0))
           (alien-funcall (extern-alien "varint_unpacker_init"
-                                       (function void (* long)
-                                                 (unsigned #.sb-vm:n-word-bits)))
+                                       (function void (* word) word))
                          unpacker
                          (sb-kernel:get-lisp-obj-address packed-int))
           (sb-int:collect ((unpacked))
@@ -190,7 +189,7 @@
              (let ((status
                     (alien-funcall
                      (extern-alien "varint_unpack"
-                                   (function int (* long) system-area-pointer))
+                                   (function int (* word) system-area-pointer))
                      unpacker (sb-sys:vector-sap result))))
                (let ((val (aref result 0)))
                  ;; status of 0 is EOF, val = 0 means a decoded value was 0,