diff --git a/src/conf.h b/src/conf.h
index af6effcc..119d5147 100644
--- a/src/conf.h
+++ b/src/conf.h
@@ -464,6 +464,7 @@ private:
 #define UPX_F_MACH_PPC32        131
 #define UPX_F_LINUX_ELFPPC32    132
 #define UPX_F_LINUX_ELF32_ARMBE 133
+#define UPX_F_MACH_FAT          134
 
 
 // compression methods
diff --git a/src/file.h b/src/file.h
index 9910dc35..183bbb4c 100644
--- a/src/file.h
+++ b/src/file.h
@@ -60,6 +60,7 @@ public:
     int getFd() const { return _fd; }
     const char *getName() const { return _name; }
     virtual off_t st_size() const;  // { return _length; }
+    virtual void set_extent(off_t offset, off_t length);
 
 protected:
     void sopen();
@@ -68,7 +69,6 @@ protected:
     virtual void write(const void *buf, int len);
     virtual void seek(off_t off, int whence);
     virtual off_t tell() const;
-    virtual void set_extent(off_t offset, off_t length);
 
     int _fd;
     int _flags;
diff --git a/src/p_mach.cpp b/src/p_mach.cpp
index 5a4cd5c9..361c9035 100644
--- a/src/p_mach.cpp
+++ b/src/p_mach.cpp
@@ -618,6 +618,128 @@ bool PackMachBase<T>::canPack()
 
 template class PackMachBase<MachClass_BE32>;
 template class PackMachBase<MachClass_LE32>;
+
+
+PackMachFat::PackMachFat(InputFile *f) : super(f)
+{
+    bele = &N_BELE_RTP::le_policy;  // sham
+}
+
+PackMachFat::~PackMachFat()
+{
+}
+
+const int *PackMachFat::getCompressionMethods(int /*method*/, int /*level*/) const
+{
+    static const int m_nrv2e[] = { M_NRV2E_LE32, M_END };
+    return m_nrv2e;  // sham
+}
+
+const int *PackMachFat::getFilters() const
+{
+    static const int filters[] = { 0x49, FT_END };
+    return filters;  // sham
+}
+
+void PackMachFat::pack(OutputFile *fo)
+{
+    fo->write(&fat_head, sizeof(fat_head.fat) +
+        fat_head.fat.nfat_arch * sizeof(fat_head.arch[0]));
+    for (unsigned j=0; j < fat_head.fat.nfat_arch; ++j) {
+        unsigned base = fo->getBytesWritten();
+        base += ~(~0u<<fat_head.arch[j].align) & -base;
+        fo->seek(base, SEEK_SET);
+        fo->set_extent(base, ~0u);
+
+        fi->set_extent(fat_head.arch[j].offset, fat_head.arch[j].size);
+        switch (fat_head.arch[j].cputype) {
+        case PackMachFat::CPU_TYPE_I386: {
+            PackMachI386 packer(fi);
+            packer.initPackHeader();
+            packer.canPack();
+            packer.updatePackHeader();
+            packer.pack(fo);
+        } break;
+        case PackMachFat::CPU_TYPE_POWERPC: {
+            PackMachPPC32 packer(fi);
+            packer.initPackHeader();
+            packer.canPack();
+            packer.updatePackHeader();
+            packer.pack(fo);
+        } break;
+        }  // switch cputype
+        fat_head.arch[j].offset = base;
+        fat_head.arch[j].size = fo->getBytesWritten() - base;
+    }
+    fo->set_extent(0, ~0u);
+    fo->seek(0, SEEK_SET);
+    fo->write(&fat_head, sizeof(fat_head.fat) +
+        fat_head.fat.nfat_arch * sizeof(fat_head.arch[0]));
+}
+
+void PackMachFat::unpack(OutputFile */*fo*/)
+{
+    assert(false);
+}
+
+bool PackMachFat::canPack()
+{
+    struct Mach_fat_arch *arch = &fat_head.arch[0];
+
+    fi->readx(&fat_head, sizeof(fat_head));
+    if (Mach_fat_header::FAT_MAGIC_SWAB==fat_head.fat.magic) {
+        unsigned *const p = &fat_head.fat.magic;
+        for (unsigned j = 0; j < sizeof(fat_head)/sizeof(unsigned); ++j) {
+            p[j] = acc_swab32(p[j]);
+        }
+    }
+    if (Mach_fat_header::FAT_MAGIC!=fat_head.fat.magic
+    ||  N_FAT_ARCH < fat_head.fat.nfat_arch) {
+        return false;
+    }
+    for (unsigned j=0; j < fat_head.fat.nfat_arch; ++j) {
+        fi->set_extent(fat_head.arch[j].offset, fat_head.arch[j].size);
+        switch (arch[j].cputype) {
+        default: return false;
+        case PackMachFat::CPU_TYPE_I386: {
+            PackMachI386 packer(fi);
+            if (!packer.canPack())
+                return false;
+        } break;
+        case PackMachFat::CPU_TYPE_POWERPC: {
+            PackMachPPC32 packer(fi);
+            if (!packer.canPack())
+                return false;
+        } break;
+        }  // switch cputype
+    }
+    return true;
+}
+
+int PackMachFat::canUnpack()
+{
+    return 0;
+}
+
+void PackMachFat::buildLoader(const Filter */*ft*/)
+{
+    assert(false);
+}
+
+Linker* PackMachFat::newLinker() const
+{
+    return new ElfLinkerX86;  // sham
+}
+
+void PackMachFat::list()
+{
+    assert(false);
+}
+
+void PackMachFat::fileInfo()
+{
+    assert(false);
+}
 /*
 vi:ts=4:et
 */
diff --git a/src/p_mach.h b/src/p_mach.h
index acb02a82..38eb0528 100644
--- a/src/p_mach.h
+++ b/src/p_mach.h
@@ -33,8 +33,9 @@
 // of the machine on which they were created.  We must deal with both kinds.
 struct Mach_fat_header {
     unsigned magic;
-        enum e8 {
-            FAT_MAGIC = 0xcafebabe
+        enum e8 {  // note conflict with java bytecode PackLinuxI386
+            FAT_MAGIC      = 0xcafebabe,
+            FAT_MAGIC_SWAB = 0xbebafeca,
         };
     unsigned nfat_arch;  // Number of Mach_fat_arch which follow.
 };
@@ -214,7 +215,7 @@ struct Mach_ppc_thread_state64
     Xword r16,r17,r18,r19,r20,r21,r22,r23;
     Xword r24,r25,r26,r27,r28,r29,r30,r31;
 
-    Word cr;        /* Condition register */
+    Word cr;        /* Condition register */  // FIXME: Xword?
     Xword xer;      /* User's integer exception register */
     Xword lr;       /* Link register */
     Xword ctr;      /* Count register */
@@ -236,7 +237,7 @@ struct MachClass_32
     typedef typename TP::U16 U16;
     typedef typename TP::U32 U32;
     typedef typename TP::U64 U64;
-    typedef N_Mach::MachITypes<U32, U32, U32, U32> MachITypes;
+    typedef N_Mach::MachITypes<U32, U64, U32, U32> MachITypes;
     typedef typename MachITypes::Addr Addr;
 
     // Mach types
@@ -454,6 +455,53 @@ protected:
     __attribute_packed;
 };
 
+class PackMachFat : public Packer
+{
+    typedef Packer super;
+public:
+    PackMachFat(InputFile *f);
+    virtual ~PackMachFat();
+
+    virtual int getVersion() const { return 13; }
+    virtual int getFormat() const { return UPX_F_MACH_FAT; }
+    virtual const char *getName() const { return "Mach/fat"; }
+    virtual const char *getFullName(const options_t *) const { return "fat-darwin.macho"; }
+    virtual const int *getCompressionMethods(int method, int level) const;
+    virtual const int *getFilters() const;
+
+protected:
+    // implementation
+    virtual void pack(OutputFile *fo);
+    virtual void unpack(OutputFile *fo);
+    virtual void list();
+    virtual void fileInfo();
+
+public:
+    virtual bool canPack();
+    virtual int canUnpack();
+
+protected:
+    // loader core
+    virtual void buildLoader(const Filter *ft);
+    virtual Linker* newLinker() const;
+
+protected:
+    enum { N_FAT_ARCH = 5 };
+    struct Fat_head {
+        struct Mach_fat_header fat;
+        struct Mach_fat_arch arch[N_FAT_ARCH];
+    } fat_head;
+
+    // UI handler
+    UiPacker *uip;
+
+    // linker
+    Linker *linker;
+#define WANT_MACH_HEADER_ENUM
+#include "p_mach_enum.h"
+#undef  WANT_MACH_HEADER_ENUM
+};
+
 #endif /* already included */
 
 
diff --git a/src/packmast.cpp b/src/packmast.cpp
index 58341558..9144e14e 100644
--- a/src/packmast.cpp
+++ b/src/packmast.cpp
@@ -244,7 +244,9 @@ Packer* PackMaster::visitAllPackers(visit_func_t func, InputFile *f, const optio
     }
     if ((p = func(new PackBSDI386(f), user)) != NULL)
         return p;
-    if ((p = func(new PackLinuxI386(f), user)) != NULL)
+    if ((p = func(new PackMachFat(f), user)) != NULL)  // cafebabe conflict
+        return p;
+    if ((p = func(new PackLinuxI386(f), user)) != NULL)  // cafebabe conflict
         return p;
 
     //