diff --git a/include/misc.h b/include/misc.h
index e37a858..d5fa0e2 100644
--- a/include/misc.h
+++ b/include/misc.h
@@ -46,13 +46,13 @@ extern Object False2;
 
 /* Align heap addresses */
 #ifdef ALIGN_8BYTE
-#  define ALIGN(ptr) ((ptr) = (void *)(((ptrdiff_t)(ptr) + 7) & ~7))
+#  define ALIGN(ptr) ((ptr) = (void *)(((intptr_t)(ptr) + 7) & ~7))
 #else
-#  define ALIGN(ptr) ((ptr) = (void *)(((ptrdiff_t)(ptr) + 3) & ~3))
+#  define ALIGN(ptr) ((ptr) = (void *)(((intptr_t)(ptr) + 3) & ~3))
 #endif
 
 /* Normalize stack addresses */
-#define NORM(addr)  ((ptrdiff_t)(addr) + delta)
+#define NORM(addr)  ((intptr_t)(addr) + delta)
 
 
 /* Used in special forms: */
diff --git a/include/object.h b/include/object.h
index 8734c29..407060b 100644
--- a/include/object.h
+++ b/include/object.h
@@ -51,8 +51,8 @@ typedef struct {
 #define FIXNUM(x)       ((int)(x).data)
 #define CHAR(x)         ((int)(x).data)
 
-#define POINTER(x)      ((void *)(ptrdiff_t)(x).data)
-#define SETPOINTER(x,p) ((x).data = (ptrdiff_t)(void *)(p))
+#define POINTER(x)      ((void *)(intptr_t)(x).data)
+#define SETPOINTER(x,p) ((x).data = (intptr_t)(void *)(p))
 #define SET(x,t,p)      ((x).tag = (int)t << 1, (x).data = (p))
 
 #define ISCONST(x)      ((x).tag & CONSTBIT)
@@ -68,9 +68,9 @@ typedef struct {
 #ifdef GENERATIONAL_GC
 
    typedef int gcspace_t;                 /* type for space and type arrays */
-   typedef ptrdiff_t gcptr_t;             /* type for pointers */
+   typedef intptr_t gcptr_t;              /* type for pointers */
    typedef long int pageno_t;             /* type for page numbers */
-   typedef ptrdiff_t addrarith_t;         /* type for address arithmetic */
+   typedef intptr_t addrarith_t;          /* type for address arithmetic */
 
    extern gcspace_t *space;
    extern gcspace_t current_space;
@@ -237,7 +237,7 @@ struct S_Control {
     Object gcsave;              /* vector */
     WIND *firstwind, *lastwind;
     int tailcall;
-    ptrdiff_t delta;
+    intptr_t delta;
 #ifdef GENERATIONAL_GC
     int reloc;
 #endif
diff --git a/src/dump-elf.c b/src/dump-elf.c
index c39b69b..81aaffe 100644
--- a/src/dump-elf.c
+++ b/src/dump-elf.c
@@ -151,7 +151,7 @@ Object P_Dump (Object ofile) {
         Primitive_Error ("sbrk(0) failed: ~E");
     }
     ndata     = obssp->sh_addr;
-    ndatasize = (Elf32_Addr)((ptrdiff_t)Brk_On_Dump - (ptrdiff_t)ndata);
+    ndatasize = (Elf32_Addr)((intptr_t)Brk_On_Dump - (intptr_t)ndata);
     ndataoff  = obssp->sh_offset;
 
     /* mmap new a.out file, setup pointers to ELF header, section header
@@ -272,7 +272,7 @@ Object P_Dump (Object ofile) {
             "memory" : "file"); (void)fflush (stdout);
 #endif
         if ((sp->sh_flags & (SHF_ALLOC|SHF_WRITE)) == (SHF_ALLOC|SHF_WRITE))
-            from = (void *)(ptrdiff_t)sp->sh_addr;
+            from = (void *)(intptr_t)sp->sh_addr;
         else
             from = (void *)(oaddr + sp->sh_offset);
         if (sp != ndatap && sp->sh_offset >= ndataoff)
diff --git a/src/dump.c b/src/dump.c
index 9538c1f..15b65af 100644
--- a/src/dump.c
+++ b/src/dump.c
@@ -109,7 +109,7 @@ void Init_Dump () {
     return False;\
 }
 
-#if defined(ELF)
+#if defined(HAVE_ELF)
 #  include "dump-elf.c"
 #elif defined(ECOFF)
 #  include "dump-ecoff.c"
diff --git a/src/env.c b/src/env.c
index 23b4ab5..a63e586 100644
--- a/src/env.c
+++ b/src/env.c
@@ -37,8 +37,8 @@ void Memoize_Frame (Object);
 void Memoize_Frames (Object, Object);
 void Forget_Frame (Object);
 
-#define Env_To_List(env, list) SET((list), T_Pair, (ptrdiff_t)POINTER(env))
-#define List_To_Env(list, env) SET((env), T_Environment, (ptrdiff_t)POINTER(list))
+#define Env_To_List(env, list) SET((list), T_Pair, (intptr_t)POINTER(env))
+#define List_To_Env(list, env) SET((env), T_Environment, (intptr_t)POINTER(list))
 
 Object The_Environment, Global_Environment;
 
diff --git a/src/heap-gen.c b/src/heap-gen.c
index 3fec8d2..1739d5a 100644
--- a/src/heap-gen.c
+++ b/src/heap-gen.c
@@ -528,7 +528,7 @@ void Make_Heap (int size) {
     else
         aligned_heap_ptr = heap_ptr;
 
-    SET(heap_obj, 0, (ptrdiff_t)aligned_heap_ptr);
+    SET(heap_obj, 0, (intptr_t)aligned_heap_ptr);
 
 #ifdef ARRAY_BROKEN
     pagebase = ((gcptr_t)POINTER (heap_obj)) / PAGEBYTES;
@@ -620,7 +620,7 @@ static int ExpandHeap (char *reason) {
     else
         aligned_heap_ptr = heap_ptr;
 
-    SET(heap_obj, 0, (ptrdiff_t)aligned_heap_ptr);
+    SET(heap_obj, 0, (intptr_t)aligned_heap_ptr);
 
     new_first = firstpage;
     new_last = lastpage;
@@ -931,7 +931,7 @@ Object Alloc_Object (size, type, konst) {
     MAKE_HEADER (*current_freep, s, type);
     current_freep++;
     *current_freep = Null;
-    SET (obj, type, (ptrdiff_t)current_freep);
+    SET (obj, type, (intptr_t)current_freep);
     if (big)
         current_freep = (Object*)0, current_free = 0;
     else
@@ -1038,7 +1038,7 @@ int Visit (register Object *cp) {
     if (WAS_FORWARDED (*cp)) {
         if (pageaddr != 0)
             PROTECT (pageaddr);
-        MAKEOBJ (*cp, tag, (ptrdiff_t)POINTER(*obj_ptr));
+        MAKEOBJ (*cp, tag, (intptr_t)POINTER(*obj_ptr));
         if (konst)
             SETCONST (*cp);
         return 0;
@@ -1111,8 +1111,8 @@ do_forward:
     MAKE_HEADER (*forward_freep, objwords, tag);
     forward_freep++;
     memcpy (forward_freep, obj_ptr, (objwords-1)*sizeof(Object));
-    SET (*obj_ptr, T_Broken_Heart, (ptrdiff_t)forward_freep);
-    MAKEOBJ (*cp, tag, (ptrdiff_t)forward_freep);
+    SET (*obj_ptr, T_Broken_Heart, (intptr_t)forward_freep);
+    MAKEOBJ (*cp, tag, (intptr_t)forward_freep);
     if (konst)
         SETCONST (*cp);
     forward_freep += (objwords - 1);
@@ -1155,7 +1155,7 @@ static void ScanPage (Object *currentp, Object *nextcp) {
          * words.
          */
 
-        SET(obj, t, (ptrdiff_t)cp);
+        SET(obj, t, (intptr_t)cp);
 
         switch (t) {
         case T_Symbol:
@@ -1560,7 +1560,7 @@ static void General_Collect (int initiate) {
         fpage = next (fpage);
     }
     current_freep = (Object *)PHYSPAGE (fpage);
-    SET(obj, 0, (ptrdiff_t)current_freep);
+    SET(obj, 0, (intptr_t)current_freep);
     current_freepage = OBJ_TO_PAGE (obj);
 
     /* advance spaces. Then forward all objects directly accessible
diff --git a/src/heap.c b/src/heap.c
index e97302d..0a22d3d 100644
--- a/src/heap.c
+++ b/src/heap.c
@@ -84,7 +84,7 @@ void Call_After_GC () {
         p->func();
 }
 
-void Visit_GC_List (GCNODE *list, ptrdiff_t delta) {
+void Visit_GC_List (GCNODE *list, intptr_t delta) {
     register GCNODE *gp, *p;
     register int n;
     register Object *vec;
@@ -101,7 +101,7 @@ void Visit_GC_List (GCNODE *list, ptrdiff_t delta) {
     }
 }
 
-void Visit_Wind (WIND *list, ptrdiff_t delta) {
+void Visit_Wind (WIND *list, intptr_t delta) {
     register WIND *wp, *p;
 
     for (wp = list; wp; wp = p->next) {
diff --git a/src/libelk.c b/src/libelk.c
index a49d59d..3e295ec 100644
--- a/src/libelk.c
+++ b/src/libelk.c
@@ -209,13 +209,13 @@ int main (int ac, char **av) {
             fprintf (stderr,
 "Can't restart dumped interpreter from a different machine architecture\n");
             fprintf (stderr,
-"   (Stack delta = %lld bytes).\n", (long long int)(ptrdiff_t)(stkbase - &foo));
+"   (Stack delta = %lld bytes).\n", (long long int)(intptr_t)(stkbase - &foo));
             exit (1);
         }
         /* Check if program break must be reset.
         */
-        if ((ptrdiff_t)Brk_On_Dump && (ptrdiff_t)brk (Brk_On_Dump)
-                == (ptrdiff_t)-1) {
+        if ((intptr_t)Brk_On_Dump && (intptr_t)brk (Brk_On_Dump)
+                == (intptr_t)-1) {
             perror ("brk"); exit (1);
         }
 #if defined(HP9K) && defined(CAN_DUMP) && defined(HPSHLIB)