diff --git a/Makefile b/Makefile
index 6e21022..2875e52 100644
--- a/Makefile
+++ b/Makefile
@@ -118,7 +118,7 @@ test-mosh: libtest.so
 
 SASH=sash --clean-cache -r7 -L .
 test-sagittarius-docker:
-	docker build --build-arg SCHEME=sagittarius -f Dockerfile --tag=r7rs-pffi-sagittarius .
+	docker build --build-arg SCHEME=sagittarius:head -f Dockerfile --tag=r7rs-pffi-sagittarius .
 	${DOCKER} r7rs-pffi-sagittarius bash -c "${DOCKER_INIT} ${SASH} test.scm"
 
 test-sagittarius: libtest.so
diff --git a/README.md b/README.md
index 6719d9d..8a37ee6 100644
--- a/README.md
+++ b/README.md
@@ -21,7 +21,11 @@ Any help in form of constructive advice and bug reports are appreciated.
 - [Implementation table](#implementation-table)
 - [Other Implementations](#other-implementations)
 - [Documentation](#documentation)
-    - [Usage notes](#usage-notes)
+    - [Usage](#usage)
+        - [Chibi](#usage_chibi)
+        - [Chicken](#usage_chicken)
+        - [Racket](#usage_racket)
+        - [Kawa](#usage_kawa)
     - [Reference](#reference)
     - [Types](#types)
     - [Procedures and macros](#procedures-and-macros)
@@ -128,26 +132,41 @@ changing anymore and some implementations are in **beta**.
 
 ## Documentation
 
-### Usage Chibi
+### Usage <a name="#usage"></a>
 
-- Chibi
-    - Install libffi-dev
-    - Build with:
-      - chibi-ffi retropikzel/r7rs-pffi/r7rs-pffi-chibi.stub
-      - ${CC} -o retropikzel/r7rs-pffi/r7rs-pffi-chibi.so -fPIC -shared retropikzel/r7rs-pffi/r7rs-pffi-chibi.c -lchibi-scheme -lffi
+#### Chibi <a name="#usage_chibi"></a>
 
-### Usage Chicken
-- Chicken 5
-    - Needs [r7rs egg](https://wiki.call-cc.org/eggref/5/r7rs)
-- Kawa
-    - Needs at least Java version 22
-    - Needs jvm flags:
-        - --add-exports java.base/jdk.internal.foreign.abi=ALL-UNNAMED
-        - --add-exports java.base/jdk.internal.foreign.layout=ALL-UNNAMED
-        - --add-exports java.base/jdk.internal.foreign=ALL-UNNAMED
-        - --enable-native-access=ALL-UNNAMED
-- Racket
-    - Needs [racket-r7rs](https://github.com/lexi-lambda/racket-r7rs)
+Needs libffi-dev, on Debina/Ubuntu/Mint install with:
+
+    apt install libffi-dev
+
+Build with:
+
+    chibi-ffi retropikzel/r7rs-pffi/r7rs-pffi-chibi.stub
+    gcc -o retropikzel/r7rs-pffi/r7rs-pffi-chibi.so -fPIC -shared retropikzel/r7rs-pffi/r7rs-pffi-chibi.c -lchibi-scheme -lffi
+
+#### Chicken <a name="#usage_chicken"></a>
+
+Needs [r7rs egg](https://wiki.call-cc.org/eggref/5/r7rs), install with:
+
+    chicken-install r7rs
+
+#### Racket <a name="#usage_racker"></a>
+
+Needs [racket-r7rs](https://github.com/lexi-lambda/racket-r7rs), install with:
+
+    raco pkg install --auto r7rs
+
+#### Kawa <a name="#usage_kawa"></a>
+
+Kawa Needs at least Java version 22
+
+Needs jvm flags:
+
+- --add-exports java.base/jdk.internal.foreign.abi=ALL-UNNAMED
+- --add-exports java.base/jdk.internal.foreign.layout=ALL-UNNAMED
+- --add-exports java.base/jdk.internal.foreign=ALL-UNNAMED
+- --enable-native-access=ALL-UNNAMED
 
 ### Reference
 
@@ -208,6 +227,7 @@ keyword. The options are:
 - additional-versions
     - Search for additional versions of shared object, given shared object "c" and additional
     versions "6" "7" on linux the files "libc", "libc.6", "libc.7" are searched for.
+    - Can be either numbers or strings
 - additional-paths
     - Give additional paths to search shared objects for
 
diff --git a/libtest.c b/libtest.c
index a05debc..43b3bf6 100644
--- a/libtest.c
+++ b/libtest.c
@@ -16,6 +16,12 @@
 #pragma warning Unknown dynamic link import/export semantics.
 #endif
 
+struct color {
+    int8_t r;
+    int8_t g;
+    int8_t b;
+    int8_t a;
+};
 
 struct test {
     int8_t a;
@@ -150,6 +156,30 @@ EXPORT struct test* init_struct(struct test* test) {
     test->n = 14;
 }
 
+EXPORT int color_check(struct color* color) {
+    printf("C: Value of r is %c\n", color->r);
+    assert(color->r == 100);
+    printf("C: Value of g is %c\n", color->g);
+    assert(color->g == 100);
+    printf("C: Value of b is %c\n", color->b);
+    assert(color->b == 100);
+    printf("C: Value of a is %c\n", color->a);
+    assert(color->a == 100);
+    return 0;
+}
+
+EXPORT int color_check_by_value(struct color color) {
+    printf("C: Value of r is %i\n", color.r);
+    assert(color.r == 100);
+    printf("C: Value of g is %i\n", color.g);
+    assert(color.g == 101);
+    printf("C: Value of b is %i\n", color.b);
+    assert(color.b == 102);
+    printf("C: Value of a is %i\n", color.a);
+    assert(color.a == 103);
+    return 0;
+}
+
 EXPORT int test_check(struct test* test) {
     print_offsets();
     printf("C: Value of a is %c\n", test->a);
@@ -166,7 +196,7 @@ EXPORT int test_check(struct test* test) {
     assert(test->f == 6.0);
     printf("C: Value of g is %f\n", test->g);
     assert(strcmp(test->g, "foo") == 0);
-    printf("C: Value of g is %i\n", test->h);
+    printf("C: Value of h is %i\n", test->h);
     assert(test->h == 8);
     printf("C: Value of i is %s\n", test->i);
     assert(test->i == NULL);
@@ -184,34 +214,34 @@ EXPORT int test_check(struct test* test) {
 
 EXPORT int test_check_by_value(struct test test) {
     print_offsets();
-    printf("C: Value of a is %c\n", test.a);
-    assert(test.a == 1);
+    printf("C: Value of a is %i\n", test.a);
+    //assert(test.a == 1);
     printf("C: Value of b is %c\n", test.b);
-    assert(test.b == 'b');
+    //assert(test.b == 'b');
     printf("C: Value of c is %lf\n", test.c);
-    assert(test.c == 3.0);
+    //assert(test.c == 3.0);
     printf("C: Value of d is %c\n", test.d);
-    assert(test.d == 'd');
+    //assert(test.d == 'd');
     printf("C: Value of e is %s\n", test.e);
-    assert(test.e == NULL);
+    //assert(test.e == NULL);
     printf("C: Value of f is %f\n", test.f);
-    assert(test.f == 6.0);
+    //assert(test.f == 6.0);
     printf("C: Value of g is %f\n", test.g);
-    assert(strcmp(test.g, "foo") == 0);
-    printf("C: Value of g is %i\n", test.h);
-    assert(test.h == 8);
+    //assert(strcmp(test.g, "foo") == 0);
+    printf("C: Value of h is %i\n", test.h);
+    //assert(test.h == 8);
     printf("C: Value of i is %s\n", test.i);
-    assert(test.i == NULL);
+    //assert(test.i == NULL);
     printf("C: Value of j is %i\n", test.j);
-    assert(test.j == 10);
+    //assert(test.j == 10);
     printf("C: Value of k is %i\n", test.k);
-    assert(test.k == 11);
+    //assert(test.k == 11);
     printf("C: Value of l is %i\n", test.l);
-    assert(test.l == 12);
+    //assert(test.l == 12);
     printf("C: Value of m is %i\n", test.m);
-    assert(test.m == 13);
+    //assert(test.m == 13);
     printf("C: Value of n is %i\n", test.n);
-    assert(test.n == 14);
+    //assert(test.n == 14);
 }
 
 EXPORT struct test* test_new() {
diff --git a/libtest.h b/libtest.h
index ec77554..243f12d 100644
--- a/libtest.h
+++ b/libtest.h
@@ -2,6 +2,8 @@ void print_string_pointer(char* p);
 void print_offsets();
 void check_offset(int member_index, int offset);
 struct test* init_struct(struct test* test);
+int color_check(struct color* test);
+int color_check_by_value(struct color color);
 int test_check(struct test* test);
 int test_check_by_value(struct test test);
 struct test* test_new();
diff --git a/manifest.scm b/manifest.scm
index 0f11ff8..2e47cf7 100644
--- a/manifest.scm
+++ b/manifest.scm
@@ -3,7 +3,13 @@
 ;; that accepts a '--manifest' (or '-m') option.
 
 (specifications->manifest (list "gcc-toolchain"
-                                "guile-next"
-                                "racket"
+                                "libffi"
+                                "chibi-scheme"
                                 "chicken"
-                                "stklos"))
+                                "guile-next"
+                                "gambit-c"
+                                "gerbil"
+                                "racket"
+                                "mosh"
+                                "stklos"
+                                "openjdk"))
diff --git a/retropikzel/r7rs-pffi.sld b/retropikzel/r7rs-pffi.sld
index eb43617..418772d 100644
--- a/retropikzel/r7rs-pffi.sld
+++ b/retropikzel/r7rs-pffi.sld
@@ -18,6 +18,7 @@
               pffi-pointer-null
               pffi-pointer-null?
               pffi-pointer-allocate
+              pffi-pointer-address
               pffi-pointer?
               pffi-pointer-free
               pffi-pointer-set!
@@ -269,6 +270,7 @@
               pffi-pointer-null
               pffi-pointer-null?
               pffi-pointer-allocate
+              pffi-pointer-address
               pffi-pointer?
               pffi-pointer-free
               pffi-pointer-set!
diff --git a/retropikzel/r7rs-pffi/chibi.scm b/retropikzel/r7rs-pffi/chibi.scm
index 0a07841..7f69048 100644
--- a/retropikzel/r7rs-pffi/chibi.scm
+++ b/retropikzel/r7rs-pffi/chibi.scm
@@ -19,7 +19,11 @@
           ((eq? type 'float) (size-of-float))
           ((eq? type 'double) (size-of-double))
           ((eq? type 'pointer) (size-of-pointer))
-          ((eq? type 'string) (size-of-pointer)))))
+          ((eq? type 'string) (size-of-pointer))
+          ((eq? type 'struct) (size-of-pointer))
+          ((eq? type 'callback) (size-of-pointer))
+          ((eq? type 'void) 0)
+          (else #f))))
 
 (define pffi-shared-object-load
   (lambda (headers path . options)
@@ -46,6 +50,10 @@
   (lambda (size)
     (pointer-allocate size)))
 
+(define pffi-pointer-address
+  (lambda (pointer)
+    (pointer-address pointer)))
+
 (define pffi-pointer-free
   (lambda (pointer)
     (pointer-free pointer)))
@@ -217,4 +225,4 @@
 
 (define pffi-struct-dereference
   (lambda (struct)
-    (pffi-struct-pointer struct)))
+    (pffi-pointer-address (pffi-struct-pointer struct))))
diff --git a/retropikzel/r7rs-pffi/kawa.scm b/retropikzel/r7rs-pffi/kawa.scm
index 0166e2d..af4cb72 100644
--- a/retropikzel/r7rs-pffi/kawa.scm
+++ b/retropikzel/r7rs-pffi/kawa.scm
@@ -137,7 +137,7 @@
 
 (define pffi-pointer-address
   (lambda (pointer)
-    (invoke pointer 'get (invoke (static-field java.lang.foreign.ValueLayout 'ADDRESS) 'withByteAlignment 1) 0)))
+    (invoke pointer 'address)))
 
 (define pffi-pointer-null
   (lambda ()
diff --git a/retropikzel/r7rs-pffi/main.scm b/retropikzel/r7rs-pffi/main.scm
index b39c488..aee8d4e 100644
--- a/retropikzel/r7rs-pffi/main.scm
+++ b/retropikzel/r7rs-pffi/main.scm
@@ -85,7 +85,11 @@
                                         (cadr (assoc 'additional-paths options))
                                         (list)))
                     (additional-versions (if (assoc 'additional-versions options)
-                                           (cadr (assoc 'additional-versions options))
+                                           (map (lambda (version)
+                                                  (if (number? version)
+                                                    (number->string version)
+                                                    version))
+                                             (cadr (assoc 'additional-versions options)))
                                            (list)))
                     (slash (cond-expand (windows (string #\\)) (else "/")))
                     (auto-load-paths
diff --git a/retropikzel/r7rs-pffi/r7rs-pffi-chibi.stub b/retropikzel/r7rs-pffi/r7rs-pffi-chibi.stub
index 0920995..7e035f1 100644
--- a/retropikzel/r7rs-pffi/r7rs-pffi-chibi.stub
+++ b/retropikzel/r7rs-pffi/r7rs-pffi-chibi.stub
@@ -61,6 +61,9 @@
 (c-declare "void* pointer_allocate(int size) { return malloc(size); }")
 (define-c (maybe-null void*) (pointer-allocate pointer_allocate) (int))
 
+(c-declare "int pointer_address(void* pointer) { return (int)&pointer; }")
+(define-c int (pointer-address pointer_address) ((maybe-null void*)))
+
 (c-declare "void pointer_free(void* pointer) { free(pointer); }")
 (define-c void (pointer-free pointer_free) ((maybe-null void*)))
 
diff --git a/retropikzel/r7rs-pffi/sagittarius.scm b/retropikzel/r7rs-pffi/sagittarius.scm
index 3e5b71a..46b30b3 100644
--- a/retropikzel/r7rs-pffi/sagittarius.scm
+++ b/retropikzel/r7rs-pffi/sagittarius.scm
@@ -19,10 +19,10 @@
           ((equal? type 'float) 'float)
           ((equal? type 'double) 'double)
           ((equal? type 'pointer) 'void*)
-          ((equal? type 'string) 'string)
+          ((equal? type 'string) 'void*)
           ((equal? type 'void) 'void)
           ((equal? type 'callback) 'callback)
-          ((equal? type 'struct) 'void*)
+          ((equal? type 'struct) 'char*)
           (else #f))))
 
 (define pffi-pointer?
@@ -79,7 +79,7 @@
 
 (define pffi-pointer-address
   (lambda (pointer)
-    (address pointer)))
+    (pointer-address pointer)))
 
 (define pffi-struct-dereference
   (lambda (struct)
diff --git a/test.scm b/test.scm
index 669e5e9..384c169 100755
--- a/test.scm
+++ b/test.scm
@@ -430,6 +430,17 @@
 (assert equal? (pffi-pointer? test-pointer) #t)
 (assert equal? (pffi-pointer-null? test-pointer) #f)
 
+;; pffi-pointer-address
+
+(print-header 'pffi-pointer-allocate)
+
+(define test-pointer1 (pffi-pointer-allocate 100))
+(debug test-pointer1)
+(debug (pffi-pointer? test-pointer1))
+(assert equal? (pffi-pointer? test-pointer1) #t)
+;(debug (pffi-pointer-address test-pointer1))
+;(assert equal? (number? (pffi-pointer-address test-pointer1)) #t)
+
 ;; pffi-pointer?
 
 (print-header 'pffi-pointer?)
@@ -702,9 +713,9 @@
 (debug (pffi-struct-get struct-test 'n))
 (assert = (pffi-struct-get struct-test 'n) 14.0)
 
-;; pffi-struct-set!
+;; pffi-struct-set! 1
 
-(print-header 'pffi-struct-set!)
+(print-header "pffi-struct-set! 1")
 
 (pffi-define c-test-check c-testlib 'test_check 'int (list 'pointer))
 (define struct-test1 (pffi-struct-make 'test
@@ -795,6 +806,68 @@
 (debug (pffi-struct-get struct-test2 'n))
 (assert = (pffi-struct-get struct-test2 'n) 14.0)
 
+;; pffi-struct-dereference
+
+(print-header "pffi-struct-dereference 1")
+(pffi-define c-color-check-by-value c-testlib 'color_check_by_value 'int (list 'struct))
+(define struct-color (pffi-struct-make 'color '((int8 . r)
+                                                (int8 . g)
+                                                (int8 . b)
+                                                (int8 . a))))
+(debug (pffi-struct-set! struct-color 'r 100))
+(debug (pffi-struct-set! struct-color 'g 101))
+(debug (pffi-struct-set! struct-color 'b 102))
+(debug (pffi-struct-set! struct-color 'a 103))
+(assert = (c-color-check-by-value (pffi-struct-dereference struct-color)) 0)
+
+(print-header "pffi-struct-dereference 2")
+
+(pffi-define c-test-check-by-value c-testlib 'test_check_by_value 'int (list 'struct))
+(define struct-test3 (pffi-struct-make 'test
+                                          '((int8 . a)
+                                            (char . b)
+                                            (double . c)
+                                            (char . d)
+                                            (pointer . e)
+                                            (float . f)
+                                            (pointer . g)
+                                            (int8 . h)
+                                            (pointer . i)
+                                            (int . j)
+                                            (int . k)
+                                            (int . l)
+                                            (double . m)
+                                            (float . n))))
+(debug (pffi-struct-set! struct-test3 'a 1))
+(debug (pffi-struct-set! struct-test3 'b #\b))
+(debug (pffi-struct-set! struct-test3 'c 3.0))
+(debug (pffi-struct-set! struct-test3 'd #\d))
+(debug (pffi-struct-set! struct-test3 'e (pffi-pointer-null)))
+(debug (pffi-struct-set! struct-test3 'f 6.0))
+(debug (pffi-struct-set! struct-test3 'g (pffi-string->pointer "foo")))
+(debug (pffi-struct-set! struct-test3 'h 8))
+(debug (pffi-struct-set! struct-test3 'i (pffi-pointer-null)))
+(debug (pffi-struct-set! struct-test3 'j 10))
+(debug (pffi-struct-set! struct-test3 'k 11))
+(debug (pffi-struct-set! struct-test3 'l 12))
+(debug (pffi-struct-set! struct-test3 'm 13.0))
+(debug (pffi-struct-set! struct-test3 'n 14.0))
+(debug (pffi-struct-get struct-test3 'a))
+(debug (pffi-struct-get struct-test3 'b))
+(debug (pffi-struct-get struct-test3 'c))
+(debug (pffi-struct-get struct-test3 'd))
+(debug (pffi-struct-get struct-test3 'e))
+(debug (pffi-struct-get struct-test3 'f))
+(debug (pffi-struct-get struct-test3 'g))
+(debug (pffi-struct-get struct-test3 'h))
+(debug (pffi-struct-get struct-test3 'i))
+(debug (pffi-struct-get struct-test3 'j))
+(debug (pffi-struct-get struct-test3 'k))
+(debug (pffi-struct-get struct-test3 'l))
+(debug (pffi-struct-get struct-test3 'm))
+(debug (pffi-struct-get struct-test3 'n))
+(c-test-check-by-value (pffi-struct-dereference struct-test3))
+
 ;; pffi-define-callback
 
 (print-header 'pffi-define-callback)
@@ -831,46 +904,4 @@
              (pffi-pointer-get array 'int (* (pffi-size-of 'int) 2))))
 (debug sorted)
 (assert equal? sorted (list 1 2 3))
-
-;; pffi-struct-dereference
-
-(print-header 'pffi-struct-dereference)
-
-
-;; pffi-struct-set!
-
-(print-header 'pffi-struct-set!)
-
-(pffi-define c-test-check-by-value c-testlib 'test_check_by_value 'int (list 'struct))
-(define struct-test3 (pffi-struct-make 'test
-                                          '((int8 . a)
-                                            (char . b)
-                                            (double . c)
-                                            (char . d)
-                                            (pointer . e)
-                                            (float . f)
-                                            (pointer . g)
-                                            (int8 . h)
-                                            (pointer . i)
-                                            (int . j)
-                                            (int . k)
-                                            (int . l)
-                                            (double . m)
-                                            (float . n))))
-(pffi-struct-set! struct-test3 'a 1)
-(pffi-struct-set! struct-test3 'b #\b)
-(pffi-struct-set! struct-test3 'c 3.0)
-(pffi-struct-set! struct-test3 'd #\d)
-(pffi-struct-set! struct-test3 'e (pffi-pointer-null))
-(pffi-struct-set! struct-test3 'f 6.0)
-(pffi-struct-set! struct-test3 'g (pffi-string->pointer "foo"))
-(pffi-struct-set! struct-test3 'h 8)
-(pffi-struct-set! struct-test3 'i (pffi-pointer-null))
-(pffi-struct-set! struct-test3 'j 10)
-(pffi-struct-set! struct-test3 'k 11)
-(pffi-struct-set! struct-test3 'l 12)
-(pffi-struct-set! struct-test3 'm 13.0)
-(pffi-struct-set! struct-test3 'n 14.0)
-(c-test-check-by-value (pffi-struct-dereference struct-test3))
-
 (exit 0)