diff --git a/Makefile b/Makefile
index d82b9a1..8166af0 100644
--- a/Makefile
+++ b/Makefile
@@ -21,15 +21,15 @@ test-compile-r7rs-docker:
 	docker build --build-arg COMPILE_R7RS=${COMPILE_R7RS} --tag=r7rs-pffi-test-${COMPILE_R7RS} -f Dockerfile.test .
 	docker run -v "${PWD}":/workdir -w /workdir -t r7rs-pffi-test-${COMPILE_R7RS} sh -c "make COMPILE_R7RS=${COMPILE_R7RS} test-compile-r7rs"
 
-tmp/test/libtest.o:
+tmp/test/libtest.o: tests/c-src/libtest.c
 	mkdir -p tmp/test
 	${CC} -o tmp/test/libtest.o -fPIC -c tests/c-src/libtest.c -I./include
 
-tmp/test/libtest.so:
+tmp/test/libtest.so: tests/c-src/libtest.c
 	mkdir -p tmp/test
 	${CC} -o tmp/test/libtest.so -shared -fPIC tests/c-src/libtest.c -I./include
 
-tmp/test/libtest.a: tmp/test/libtest.o
+tmp/test/libtest.a: tmp/test/libtest.o tests/c-src/libtest.c
 	ar rcs tmp/test/libtest.a tmp/test/libtest.o
 
 
diff --git a/tests/c-src/libtest.c b/tests/c-src/libtest.c
new file mode 100644
index 0000000..35c71df
--- /dev/null
+++ b/tests/c-src/libtest.c
@@ -0,0 +1,293 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <assert.h>
+#include <string.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#if defined(_MSC_VER)
+#define EXPORT __declspec(dllexport)
+#define IMPORT __declspec(dllimport)
+#elif defined(__GNUC__)
+#define EXPORT __attribute__((visibility("default")))
+#define IMPORT
+#else
+#define EXPORT
+#define IMPORT
+#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;
+    char b;
+    double c;
+    char d;
+    void* e;
+    float f;
+    char* g;
+    int8_t h;
+    void* i;
+    int j;
+    int k;
+    int l;
+    double m;
+    float n;
+};
+
+void print_string_pointer(char* p) {
+    printf("C print_string_pointer: %s\n", p);
+}
+
+void print_offsets() {
+    printf("C: Offset of a = %u\n", offsetof(struct test, a));
+    printf("C: Offset of b = %u\n", offsetof(struct test, b));
+    printf("C: Offset of c = %u\n", offsetof(struct test, c));
+    printf("C: Offset of d = %u\n", offsetof(struct test, d));
+    printf("C: Offset of e = %u\n", offsetof(struct test, e));
+    printf("C: Offset of f = %u\n", offsetof(struct test, f));
+    printf("C: Offset of g = %u\n", offsetof(struct test, g));
+    printf("C: Offset of h = %u\n", offsetof(struct test, h));
+    printf("C: Offset of i = %u\n", offsetof(struct test, i));
+    printf("C: Offset of j = %u\n", offsetof(struct test, j));
+    printf("C: Offset of k = %u\n", offsetof(struct test, k));
+    printf("C: Offset of l = %u\n", offsetof(struct test, l));
+    printf("C: Offset of m = %u\n", offsetof(struct test, m));
+    printf("C: Offset of n = %u\n", offsetof(struct test, n));
+}
+
+void check_offset(int member_index, int offset) {
+    if (member_index == 1) {
+        int true_offset = offsetof(struct test, a);
+        printf("C: Checking that member_index : %u, is offset: %u, true offset: %u\n", member_index, offset, true_offset);
+        fflush(stdout);
+        assert(true_offset == offset);
+    } else if (member_index == 2) {
+        int true_offset = offsetof(struct test, b);
+        printf("C: Checking that member_index : %u, is offset: %u, true offset: %u\n", member_index, offset, true_offset);
+        fflush(stdout);
+        assert(true_offset == offset);
+    } else if (member_index == 3) {
+        int true_offset = offsetof(struct test, c);
+        printf("C: Checking that member_index : %u, is offset: %u, true offset: %u\n", member_index, offset, true_offset);
+        fflush(stdout);
+        assert(true_offset == offset);
+    } else if (member_index == 4) {
+        int true_offset = offsetof(struct test, d);
+        printf("C: Checking that member_index : %u, is offset: %u, true offset: %u\n", member_index, offset, true_offset);
+        fflush(stdout);
+        assert(true_offset == offset);
+    } else if (member_index == 5) {
+        int true_offset = offsetof(struct test, e);
+        printf("C: Checking that member_index : %u, is offset: %u, true offset: %u\n", member_index, offset, true_offset);
+        fflush(stdout);
+        assert(true_offset == offset);
+    } else if (member_index == 6) {
+        int true_offset = offsetof(struct test, f);
+        printf("C: Checking that member_index : %u, is offset: %u, true offset: %u\n", member_index, offset, true_offset);
+        fflush(stdout);
+        assert(true_offset == offset);
+    } else if (member_index == 7) {
+        int true_offset = offsetof(struct test, g);
+        printf("C: Checking that member_index : %u, is offset: %u, true offset: %u\n", member_index, offset, true_offset);
+        fflush(stdout);
+        assert(true_offset == offset);
+    } else if (member_index == 8) {
+        int true_offset = offsetof(struct test, h);
+        printf("C: Checking that member_index : %u, is offset: %u, true offset: %u\n", member_index, offset, true_offset);
+        fflush(stdout);
+        assert(true_offset == offset);
+    } else if (member_index == 9) {
+        int true_offset = offsetof(struct test, i);
+        printf("C: Checking that member_index : %u, is offset: %u, true offset: %u\n", member_index, offset, true_offset);
+        fflush(stdout);
+        assert(true_offset == offset);
+    } else if (member_index == 10) {
+        int true_offset = offsetof(struct test, j);
+        printf("C: Checking that member_index : %u, is offset: %u, true offset: %u\n", member_index, offset, true_offset);
+        fflush(stdout);
+        assert(true_offset == offset);
+    } else if (member_index == 11) {
+        int true_offset = offsetof(struct test, k);
+        printf("C: Checking that member_index : %u, is offset: %u, true offset: %u\n", member_index, offset, true_offset);
+        fflush(stdout);
+        assert(true_offset == offset);
+    } else if (member_index == 12) {
+        int true_offset = offsetof(struct test, l);
+        printf("C: Checking that member_index : %u, is offset: %u, true offset: %u\n", member_index, offset, true_offset);
+        fflush(stdout);
+        assert(true_offset == offset);
+    } else if (member_index == 13) {
+        int true_offset = offsetof(struct test, m);
+        printf("C: Checking that member_index : %u, is offset: %u, true offset: %u\n", member_index, offset, true_offset);
+        fflush(stdout);
+        assert(true_offset == offset);
+    } else if (member_index == 14) {
+        int true_offset = offsetof(struct test, n);
+        printf("C: Checking that member_index : %u, is offset: %u, true offset: %u\n", member_index, offset, true_offset);
+        fflush(stdout);
+        assert(true_offset == offset);
+    }
+}
+
+
+EXPORT struct test* init_struct(struct test* test) {
+    print_offsets();
+    test->a = 1;
+    test->b = 'b';
+    test->c = 3.0;
+    test->d = 'd';
+    test->e = NULL;
+    test->f = 6.0;
+    char* foo = malloc(sizeof("FOOBAR"));
+    snprintf(foo, sizeof("FOOBAR") + 1, "FOOBAR");
+    test->g = foo;
+    test->h = 8;
+    test->i = NULL;
+    test->j = 10;
+    test->k = 11;
+    test->l = 12;
+    test->m = 13;
+    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 == 101);
+    printf("C: Value of b is %c\n", color->b);
+    assert(color->b == 102);
+    printf("C: Value of a is %c\n", color->a);
+    assert(color->a == 103);
+    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);
+    assert(test->a == 1);
+    printf("C: Value of b is %c\n", test->b);
+    assert(test->b == 'b');
+    printf("C: Value of c is %lf\n", test->c);
+    //FIXME
+    //assert(test->c == 3.0);
+    printf("C: Value of d is %c\n", test->d);
+    assert(test->d == 'd');
+    printf("C: Value of e is %s\n", test->e);
+    assert(test->e == NULL);
+    printf("C: Value of f is %f\n", test->f);
+    //FIXME
+    //assert(test->f == 6.0);
+    //FIXME
+    //printf("C: Value of g is %f\n", test->g);
+    //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);
+    //FIXME
+    //printf("C: Value of j is %i\n", test->j);
+    //assert(test->j == 10);
+    //FIXME
+    //printf("C: Value of k is %i\n", test->k);
+    //assert(test->k == 11);
+    //FIXME
+    //printf("C: Value of l is %i\n", test->l);
+    //assert(test->l == 12);
+    //FIXME
+    //printf("C: Value of m is %i\n", test->m);
+    //assert(test->m == 13);
+    //FIXME
+    //printf("C: Value of n is %i\n", test->n);
+    //assert(test->n == 14);
+}
+
+EXPORT int test_check_by_value(struct test test) {
+    print_offsets();
+    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');
+    printf("C: Value of c is %lf\n", test.c);
+    assert(test.c == 3.0);
+    printf("C: Value of d is %c\n", test.d);
+    assert(test.d == 'd');
+    printf("C: Value of e is %s\n", test.e);
+    assert(test.e == NULL);
+    printf("C: Value of f is %f\n", test.f);
+    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 h is %i\n", test.h);
+    assert(test.h == 8);
+    printf("C: Value of i is %s\n", test.i);
+    assert(test.i == NULL);
+    printf("C: Value of j is %i\n", test.j);
+    assert(test.j == 10);
+    printf("C: Value of k is %i\n", test.k);
+    assert(test.k == 11);
+    printf("C: Value of l is %i\n", test.l);
+    assert(test.l == 12);
+    printf("C: Value of m is %i\n", test.m);
+    assert(test.m == 13);
+    printf("C: Value of n is %i\n", test.n);
+    assert(test.n == 14);
+}
+
+EXPORT struct test* test_new() {
+    print_offsets();
+    struct test* t = malloc(sizeof(struct test));
+    t->a = 1;
+    t->b = 'b';
+    t->c = 3.0;
+    t->d = 'd';
+    t->e = NULL;
+    t->f = 6.0;
+    char* foo = malloc(sizeof("FOOBAR"));
+    snprintf(foo, sizeof("FOOBAR") + 1, "FOOBAR");
+    t->g = foo;
+    t->h = 8;
+    t->i = NULL;
+    t->j = 10;
+    t->k = 11;
+    t->l = 12;
+    t->m = 13;
+    t->n = 14;
+    return t;
+}
+
+EXPORT void takes_no_args() {
+    puts("I take no arguments :)");
+}
+
+EXPORT int takes_no_args_returns_int() {
+    return 0;
+}
+
+EXPORT int test_passing_pointer_address(int* p1, int** p2) {
+    printf("p1 value: %i\n", *p1);
+    printf("p2 value: %i\n", **p2);
+    int* p3 = malloc(sizeof(int));
+    *p3 = 42;
+    *p2 = p3;
+    return 0;
+}