diff --git a/configure b/configure
index 6963382..ed3916a 100755
--- a/configure
+++ b/configure
@@ -5536,6 +5536,7 @@ cat >>confdefs.h <<_ACEOF
 _ACEOF
 
 
+# remember to enable before release.
 # if (test $ac_cv_sizeof_void_p != 4); then
 #   AC_MSG_ERROR([Ikarus can only run in 32-bit mode.])
 # fi
diff --git a/configure.ac b/configure.ac
index d1a1f80..24ac877 100644
--- a/configure.ac
+++ b/configure.ac
@@ -29,6 +29,7 @@ case "$target_os" in
 
 
 AC_CHECK_SIZEOF(void *)
+# remember to enable before release.
 # if (test $ac_cv_sizeof_void_p != 4); then
 #   AC_MSG_ERROR([Ikarus can only run in 32-bit mode.])
 # fi
diff --git a/scheme/ikarus.compiler.ss b/scheme/ikarus.compiler.ss
index 888a439..dfe05c9 100644
--- a/scheme/ikarus.compiler.ss
+++ b/scheme/ikarus.compiler.ss
@@ -2059,7 +2059,11 @@
 
   ;;; refer to the picture in src/ikarus-collect.c for details
   ;;; on how call-frames are laid out.  (search for livemask)
-  (define call-instruction-size 5)
+  (define call-instruction-size 
+    (case wordsize
+      [(4) 5]
+      [(8) 10]
+      [else (die 'call-instruction-size "invalid" wordsize)]))
   (define disp-frame-size    (- (+ call-instruction-size (* 3 wordsize))))
   (define disp-frame-offset  (- (+ call-instruction-size (* 2 wordsize))))
   (define disp-multivalue-rp (- (+ call-instruction-size (* 1 wordsize))))
diff --git a/scheme/ikarus.fasl.write.ss b/scheme/ikarus.fasl.write.ss
index 38ceabb..aacedfe 100644
--- a/scheme/ikarus.fasl.write.ss
+++ b/scheme/ikarus.fasl.write.ss
@@ -64,18 +64,19 @@
   (define (put-tag c p)
     (write-byte (char->integer c) p))
   
-  (define write-int 
+  (define write-int32 
     (lambda (x p)
-      (unless (int? x) (die 'write-int "not a int" x))
       (write-byte (bitwise-and x #xFF) p)
       (write-byte (bitwise-and (sra x 8) #xFF) p)
       (write-byte (bitwise-and (sra x 16) #xFF) p)
-      (write-byte (bitwise-and (sra x 24) #xFF) p)
+      (write-byte (bitwise-and (sra x 24) #xFF) p)))
+ 
+  (define write-int 
+    (lambda (x p)
+      (unless (int? x) (die 'write-int "not a int" x))
+      (write-int32 x p)
       (when (eqv? wordsize 8)
-        (write-byte (bitwise-and (sra x 32) #xFF) p)
-        (write-byte (bitwise-and (sra x 40) #xFF) p)
-        (write-byte (bitwise-and (sra x 48) #xFF) p)
-        (write-byte (bitwise-and (sra x 56) #xFF) p))))
+        (write-int32 (sra x 32) p))))
 
   (define fasl-write-immediate
     (lambda (x p)
@@ -92,7 +93,7 @@
                  (write-byte n p))
                (begin
                  (put-tag #\C p)
-                 (write-int n p))))]
+                 (write-int32 n p))))]
         [(boolean? x)
          (put-tag (if x #\T #\F) p)]
         [(eof-object? x) (put-tag #\E p)]
@@ -164,7 +165,7 @@
             (write-int (string-length x) p)
             (let f ([x x] [i 0] [n (string-length x)])
               (unless (= i n)
-                (write-int (char->integer (string-ref x i)) p)
+                (write-int32 (char->integer (string-ref x i)) p)
                 (f x (fxadd1 i) n)))])
          m]
         [(gensym? x)
@@ -269,11 +270,11 @@
              [(fx> mark 0) ; marked but not written
               (hashtable-set! h x (fx- 0 m))
               (put-tag #\> p)
-              (write-int m p)
+              (write-int32 m p)
               (do-write x p h (fxadd1 m))]
              [else
               (put-tag #\< p)
-              (write-int (fx- 0 mark) p)
+              (write-int32 (fx- 0 mark) p)
               m]))]
         [else (die 'fasl-write "BUG: not in hash table" x)]))) 
   (define make-graph
diff --git a/scheme/ikarus.intel-assembler.ss b/scheme/ikarus.intel-assembler.ss
index ee14f97..db371ff 100644
--- a/scheme/ikarus.intel-assembler.ss
+++ b/scheme/ikarus.intel-assembler.ss
@@ -23,6 +23,10 @@
     (except (ikarus code-objects) procedure-annotation)
     (ikarus system $pairs))
 
+
+(module (wordsize)
+  (include "ikarus.config.ss"))
+
 (define fold
   (lambda (f init ls)
     (cond
@@ -710,9 +714,10 @@
                 (case (car x)
                   [(byte) (fx+ ac 1)]
                   [(word reloc-word reloc-word+ label-addr foreign-label 
-                    relative local-relative current-frame-offset)
+                    local-relative)
                    (fx+ ac 4)]
                   [(label) ac]
+                  [(relative current-frame-offset) (+ ac wordsize)]
                   [else (die 'compute-code-size "unknown instr" x)])))
           0 
           ls)))
@@ -784,15 +789,17 @@
                    (f (cdr ls) (fx+ idx 1) reloc)]
                   [(reloc-word reloc-word+)
                    (f (cdr ls) (fx+ idx 4) (cons (cons idx a) reloc))]
-                  [(local-relative relative label-addr foreign-label) 
+                  [(local-relative label-addr foreign-label)
                    (f (cdr ls) (fx+ idx 4) (cons (cons idx a) reloc))]
+                  [(relative)
+                   (f (cdr ls) (fx+ idx wordsize) (cons (cons idx a) reloc))]
                   [(word)
                    (let ([v (cdr a)])
                       (set-code-word! x idx v)
                       (f (cdr ls) (fx+ idx 4) reloc))]
                   [(current-frame-offset)
-                   (set-code-word! x idx idx)
-                   (f (cdr ls) (fx+ idx 4) reloc)]
+                   (set-code-word! x idx idx) ;;; FIXME 64bit
+                   (f (cdr ls) (fx+ idx wordsize) reloc)]
                   [(label)
                    (set-label-loc! (cdr a) (list x idx))
                    (f (cdr ls) idx reloc)]
@@ -800,8 +807,6 @@
                    (die 'whack-instructions "unknown instr" a)])))])))
     (f ls 0 '())))
 
-(define wordsize 4)
-
 
 (define compute-reloc-size 
   (lambda (ls)
diff --git a/scheme/last-revision b/scheme/last-revision
index 5239676..3f15424 100644
--- a/scheme/last-revision
+++ b/scheme/last-revision
@@ -1 +1 @@
-1315
+1316
diff --git a/scheme/makefile.ss b/scheme/makefile.ss
index 066837a..2770ec2 100755
--- a/scheme/makefile.ss
+++ b/scheme/makefile.ss
@@ -1,4 +1,4 @@
-#!/usr/bin/env ikarus -b ikarus.boot --r6rs-script
+#!../src/ikarus -b ikarus.boot --r6rs-script
 ;;; Ikarus Scheme -- A compiler for R6RS Scheme.
 ;;; Copyright (C) 2006,2007  Abdulaziz Ghuloum
 ;;; 
diff --git a/src/ikarus-data.h b/src/ikarus-data.h
index a56f5e3..cf3e3e6 100644
--- a/src/ikarus-data.h
+++ b/src/ikarus-data.h
@@ -219,7 +219,8 @@ ikptr ik_safe_alloc(ikpcb* pcb, int size);
 #define align(n) \
   ((((n) + align_size - 1) >>  align_shift) << align_shift)
 
-#define IK_FASL_HEADER "#@IK01"
+#define IK_FASL_HEADER \
+  ((sizeof(ikptr) == 4) ? "#@IK01" : "#@IK02")
 #define IK_FASL_HEADER_LEN (strlen(IK_FASL_HEADER))
 
 #define code_pri_tag vector_tag
@@ -351,7 +352,8 @@ ikptr ik_safe_alloc(ikpcb* pcb, int size);
 #define align_to_prev_page(x) \
   ((((unsigned long int)(x)) >> pageshift) << pageshift)
 
-#define call_instruction_size 5
+#define call_instruction_size \
+  ((wordsize == 4) ? 5 : 10)
 #define disp_frame_size   (- (call_instruction_size + 3 * wordsize))
 #define disp_frame_offset (- (call_instruction_size + 2 * wordsize))
 #define disp_multivale_rp (- (call_instruction_size + 1 * wordsize))
diff --git a/src/ikarus-fasl.c b/src/ikarus-fasl.c
index 4caf750..68ca2b6 100644
--- a/src/ikarus-fasl.c
+++ b/src/ikarus-fasl.c
@@ -110,8 +110,12 @@ void ik_fasl_load(ikpcb* pcb, char* fasl_file){
       }
       close(fd);
     }
-    ikptr val = ik_exec_code(pcb, v);
-    val = void_object;
+    ikptr val = void_object;
+    if(wordsize == 4){
+      ik_exec_code(pcb, v);
+    } else {
+      fprintf(stderr, "NOT EXECING YET\n");
+    }
     if(val != void_object){
       /* this is from revision 1 
          and is no longer needed 
@@ -123,6 +127,10 @@ void ik_fasl_load(ikpcb* pcb, char* fasl_file){
     fprintf(stderr, "fasl-read did not reach eof!\n");
     exit(-10);
   }
+  if(wordsize == 8){
+    fprintf(stderr, "DONE READING FASL, EXITING ...\n");
+    exit(-1);
+  }
 }
 
 static ikptr 
@@ -269,7 +277,7 @@ static ikptr do_read(ikpcb* pcb, fasl_port* p){
           ik_print(p->marks[idx]);
           exit(-1);
         }
-      } 
+      }
     }
     else {
       /* allocate marks */
@@ -279,9 +287,9 @@ static ikptr do_read(ikpcb* pcb, fasl_port* p){
     }
   }
   if(c == 'x'){
-    int code_size;
+    long int code_size;
     ikptr freevars;
-    fasl_read_buf(p, &code_size, sizeof(int));
+    fasl_read_buf(p, &code_size, sizeof(long int));
     fasl_read_buf(p, &freevars, sizeof(ikptr));
     ikptr annotation = do_read(pcb, p);
     ikptr code = alloc_code(align(code_size+disp_code_data), pcb, p);
@@ -317,16 +325,16 @@ static ikptr do_read(ikpcb* pcb, fasl_port* p){
   }
   else if(c == 's'){
     /* ascii string */
-    int len;
-    fasl_read_buf(p, &len, sizeof(int));
-    int size = align(len*string_char_size + disp_string_data);
+    long int len;
+    fasl_read_buf(p, &len, sizeof(long int));
+    long int size = align(len*string_char_size + disp_string_data);
     ikptr str = ik_unsafe_alloc(pcb, size) + string_tag;
     ref(str, off_string_length) = fix(len);
     fasl_read_buf(p, (char*)(long)str+off_string_data, len);
     {
       unsigned char* pi = (unsigned char*)(long)(str+off_string_data);
       ikchar* pj = (ikchar*)(long)(str+off_string_data);
-      int i = len-1;
+      long int i = len-1;
       for(i=len-1; i >= 0; i--){
         pj[i] = integer_to_char(pi[i]);
       }
@@ -339,9 +347,9 @@ static ikptr do_read(ikpcb* pcb, fasl_port* p){
   }
   else if(c == 'S'){
     /* string */
-    int len;
-    fasl_read_buf(p, &len, sizeof(int));
-    int size = align(len*string_char_size + disp_string_data);
+    long int len;
+    fasl_read_buf(p, &len, sizeof(long int));
+    long int size = align(len*string_char_size + disp_string_data);
     ikptr str = ik_unsafe_alloc(pcb, size) + string_tag;
     ref(str, off_string_length) = fix(len);
     long int i;
@@ -356,17 +364,16 @@ static ikptr do_read(ikpcb* pcb, fasl_port* p){
     }
     return str;
   }
-
   else if(c == 'V'){
-    int len;
-    fasl_read_buf(p, &len, sizeof(int));
-    int size = align(len * wordsize + disp_vector_data);
+    long int len;
+    fasl_read_buf(p, &len, sizeof(long int));
+    long int size = align(len * wordsize + disp_vector_data);
     ikptr vec = ik_unsafe_alloc(pcb, size) + vector_tag;
     if(put_mark_index){
       p->marks[put_mark_index] = vec;
     }
     ref(vec, off_vector_length) = fix(len);
-    int i;
+    long int i;
     for(i=0; i<len; i++){
       ref(vec, off_vector_data + i*wordsize) = do_read(pcb, p);
     }
@@ -374,7 +381,7 @@ static ikptr do_read(ikpcb* pcb, fasl_port* p){
   }
   else if(c == 'I'){
     ikptr fixn;
-    fasl_read_buf(p, &fixn, sizeof(int));
+    fasl_read_buf(p, &fixn, sizeof(ikptr));
     return fixn;
   }
   else if(c == 'F'){
@@ -404,8 +411,8 @@ static ikptr do_read(ikpcb* pcb, fasl_port* p){
   else if(c == 'R'){ /* R is for RTD */
     ikptr name = do_read(pcb, p);
     ikptr symb = do_read(pcb, p);
-    int i, n;
-    fasl_read_buf(p, &n, sizeof(int));
+    long int i, n;
+    fasl_read_buf(p, &n, sizeof(long int));
     ikptr fields;
     if(n == 0){
       fields = null_object;
@@ -471,9 +478,9 @@ static ikptr do_read(ikpcb* pcb, fasl_port* p){
   }
   else if(c == 'v'){
     /* bytevector */
-    int len;
-    fasl_read_buf(p, &len, sizeof(int));
-    int size = align(len + disp_bytevector_data + 1);
+    long int len;
+    fasl_read_buf(p, &len, sizeof(long int));
+    long int size = align(len + disp_bytevector_data + 1);
     ikptr x = ik_unsafe_alloc(pcb, size) + bytevector_tag;
     ref(x, off_bytevector_length) = fix(len);
     fasl_read_buf(p, (void*)(long)(x+off_bytevector_data), len);
@@ -485,10 +492,6 @@ static ikptr do_read(ikpcb* pcb, fasl_port* p){
   }
   else if(c == 'l'){
     int len = (unsigned char) fasl_read_byte(p);
-    if(len < 0){
-      fprintf(stderr, "invalid len=%d\n", len);
-      exit(-1);
-    }
     ikptr pair = ik_unsafe_alloc(pcb, pair_size * (len+1)) + pair_tag;
     if(put_mark_index){
       p->marks[put_mark_index] = pair;
@@ -504,17 +507,17 @@ static ikptr do_read(ikpcb* pcb, fasl_port* p){
     return pair;
   }
   else if(c == 'L'){
-    int len;
-    fasl_read_buf(p, &len, sizeof(int));
+    long int len;
+    fasl_read_buf(p, &len, sizeof(long int));
     if(len < 0){
-      fprintf(stderr, "invalid len=%d\n", len);
+      fprintf(stderr, "invalid len=%ld\n", len);
       exit(-1);
     }
     ikptr pair = ik_unsafe_alloc(pcb, pair_size * (len+1)) + pair_tag;
     if(put_mark_index){
       p->marks[put_mark_index] = pair;
     }
-    int i; ikptr pt = pair;
+    long int i; ikptr pt = pair;
     for(i=0; i<len; i++){
       ref(pt, off_car) = do_read(pcb, p);
       ref(pt, off_cdr) = pt + pair_size;
@@ -539,15 +542,15 @@ static ikptr do_read(ikpcb* pcb, fasl_port* p){
     return int_to_scheme_char(n);
   }
   else if(c == 'b'){
-    int len;
-    int sign = 0;
-    fasl_read_buf(p, &len, sizeof(int));
+    long int len;
+    long int sign = 0;
+    fasl_read_buf(p, &len, sizeof(long int));
     if(len < 0) {
       sign = 1;
       len = -len;
     }
     if(len & 3){
-      fprintf(stderr, "Error in fasl-read: invalid bignum length %d\n", len);
+      fprintf(stderr, "Error in fasl-read: invalid bignum length %ld\n", len);
       exit(-1);
     }
     unsigned long int tag = bignum_tag | (sign << bignum_sign_shift) | 
diff --git a/src/ikarus-runtime.c b/src/ikarus-runtime.c
index 2c840b0..29aed13 100644
--- a/src/ikarus-runtime.c
+++ b/src/ikarus-runtime.c
@@ -42,8 +42,8 @@ int total_allocated_pages = 0;
 extern char **environ;
 
 
-#define segment_size  (pagesize*pagesize/wordsize)
-#define segment_shift (pageshift+pageshift-wordshift)
+#define segment_size  (pagesize*pagesize/4)
+#define segment_shift (pageshift+pageshift-2)
 #define segment_index(x) (((unsigned long int)(x)) >> segment_shift)
 
 ikptr ik_mmap(int size);
@@ -328,9 +328,9 @@ ikpcb* ik_make_pcb(){
       hi_mem = pcb->heap_base + pcb->heap_size + pagesize;
     }
 
-    long int lo_seg = segment_index(lo_mem);
-    long int hi_seg = segment_index(hi_mem+segment_size-1);
-    long int vec_size = (hi_seg - lo_seg) * pagesize;
+    unsigned long int lo_seg = segment_index(lo_mem);
+    unsigned long int hi_seg = segment_index(hi_mem+segment_size-1);
+    unsigned long int vec_size = (hi_seg - lo_seg) * pagesize;
     ikptr dvec = ik_mmap(vec_size);
     bzero((char*)(long)dvec, vec_size);
     pcb->dirty_vector_base = (unsigned int*)(long) dvec;