diff --git a/src/map.h b/src/map.h
index 96d879547..6ce6d3685 100644
--- a/src/map.h
+++ b/src/map.h
@@ -23,6 +23,10 @@
 #define GIT_MAP_TYPE	0xf
 #define GIT_MAP_FIXED	0x10
 
+#ifdef __amigaos4__
+#define MAP_FAILED 0
+#endif
+
 typedef struct { /* memory mapped buffer	*/
 	void *data; /* data bytes			*/
 	size_t len; /* data length			*/
diff --git a/src/pack.c b/src/pack.c
index 0db1069de..85bc6707e 100644
--- a/src/pack.c
+++ b/src/pack.c
@@ -215,7 +215,7 @@ static int packfile_unpack_header1(
 	unsigned shift;
 	unsigned long size, c;
 	unsigned long used = 0;
-
+printf("[pack 218] buf = %lx, used = %ld, len = %ld\n", buf, used, len);
 	c = buf[used++];
 	*type = (c >> 4) & 7;
 	size = c & 15;
@@ -261,7 +261,7 @@ int git_packfile_unpack_header(
 	base = git_mwindow_open(mwf, w_curs, *curpos, 20, &left);
 	if (base == NULL)
 		return GIT_EBUFS;
-
+printf("[pack 264] base = %lx, mwf = %lx\n", base, mwf);
 	ret = packfile_unpack_header1(&used, size_p, type_p, base, left);
 	git_mwindow_close(w_curs);
 	if (ret == GIT_EBUFS)
diff --git a/src/unix/map.c b/src/unix/map.c
index 65f4ac91c..8e853b9be 100644
--- a/src/unix/map.c
+++ b/src/unix/map.c
@@ -16,7 +16,6 @@
 
 int p_mmap(git_map *out, size_t len, int prot, int flags, int fd, git_off_t offset)
 {
-#ifndef __amigaos4__
 	int mprot = 0;
 	int mflag = 0;
 
@@ -25,6 +24,7 @@ int p_mmap(git_map *out, size_t len, int prot, int flags, int fd, git_off_t offs
 	out->data = NULL;
 	out->len = 0;
 
+#ifndef __amigaos4__
 	if (prot & GIT_PROT_WRITE)
 		mprot = PROT_WRITE;
 	else if (prot & GIT_PROT_READ)
@@ -36,21 +36,34 @@ int p_mmap(git_map *out, size_t len, int prot, int flags, int fd, git_off_t offs
 		mflag = MAP_PRIVATE;
 
 	out->data = mmap(NULL, len, mprot, mflag, fd, offset);
+#else
+	if ((prot & GIT_PROT_WRITE) && ((flags & GIT_MAP_TYPE) == GIT_MAP_SHARED)) {
+		printf("Trying to map shared-writeable file!!!\n");
+
+		if(out->data = malloc(len)) {
+			lseek(fd, offset, SEEK_SET);
+			p_read(fd, out->data, len);
+		}
+	}
+#endif
+
 	if (!out->data || out->data == MAP_FAILED) {
 		giterr_set(GITERR_OS, "Failed to mmap. Could not write data");
 		return -1;
 	}
 
 	out->len = len;
-#endif
+
 	return 0;
 }
 
 int p_munmap(git_map *map)
 {
-#ifndef __amigaos4__
 	assert(map != NULL);
+#ifndef __amigaos4__
 	munmap(map->data, map->len);
+#else
+	free(map->data);
 #endif
 	return 0;
 }