diff --git a/CMakeLists.txt b/CMakeLists.txt
index cffa6c7e76..b071261467 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -124,6 +124,7 @@ find_package(ZLIB REQUIRED)
 
 if(APPLE)
     find_package(Security)
+    find_package(libarchive REQUIRED)
 elseif(UNIX)
     find_package(LIBSECRET)
     find_package(Uuid REQUIRED)
diff --git a/Sources/Plasma/Apps/plClient/CMakeLists.txt b/Sources/Plasma/Apps/plClient/CMakeLists.txt
index 21be8e81cf..804c597f42 100644
--- a/Sources/Plasma/Apps/plClient/CMakeLists.txt
+++ b/Sources/Plasma/Apps/plClient/CMakeLists.txt
@@ -242,6 +242,7 @@ target_link_libraries(
         CURL::libcurl
         "$<$<PLATFORM_ID:Darwin>:-framework Cocoa>"
         "$<$<PLATFORM_ID:Darwin>:-framework QuartzCore>"
+        "$<$<PLATFORM_ID:Darwin>:archive>"
 )
 target_include_directories(plClient PRIVATE "${CMAKE_CURRENT_SOURCE_DIR}")
 
diff --git a/Sources/Plasma/Apps/plClient/Mac-Cocoa/PLSPatcher.h b/Sources/Plasma/Apps/plClient/Mac-Cocoa/PLSPatcher.h
index 43fa529572..08cf3d6770 100644
--- a/Sources/Plasma/Apps/plClient/Mac-Cocoa/PLSPatcher.h
+++ b/Sources/Plasma/Apps/plClient/Mac-Cocoa/PLSPatcher.h
@@ -50,7 +50,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (void)patcher:(PLSPatcher*)patcher beganDownloadOfFile:(NSString*)file;
 - (void)patcher:(PLSPatcher*)patcher updatedProgress:(NSString*)progressMessage withBytes:(NSUInteger)bytes outOf:(uint64_t)totalBytes;
-- (void)patcherCompleted:(PLSPatcher*)patcher;
+- (void)patcherCompleted:(PLSPatcher*)patcher didSelfPatch:(BOOL)selfPatched;
 - (void)patcherCompletedWithError:(PLSPatcher*)patcher error:(NSError*)error;
 
 @end
@@ -60,6 +60,7 @@ NS_ASSUME_NONNULL_BEGIN
 @property(weak) id<PLSPatcherDelegate> delegate;
 @property(readonly) BOOL selfPatched;
 
+- (NSURL *)completeSelfPatch;
 - (void)start;
 
 @end
diff --git a/Sources/Plasma/Apps/plClient/Mac-Cocoa/PLSPatcher.mm b/Sources/Plasma/Apps/plClient/Mac-Cocoa/PLSPatcher.mm
index 552df1776e..7416bf42eb 100644
--- a/Sources/Plasma/Apps/plClient/Mac-Cocoa/PLSPatcher.mm
+++ b/Sources/Plasma/Apps/plClient/Mac-Cocoa/PLSPatcher.mm
@@ -43,6 +43,8 @@
 #import "PLSPatcher.h"
 #import "NSString+StringTheory.h"
 
+#include <archive.h>
+#include <archive_entry.h>
 #include <unordered_set>
 #include <string_theory/format>
 
@@ -61,6 +63,7 @@
     void IOnPatchComplete(ENetError result, const ST::string& msg);
     void IOnProgressTick(uint64_t curBytes, uint64_t totalBytes, const ST::string& status);
     void IOnDownloadBegin(const plFileName& file);
+    void ISelfPatch(const plFileName& file);
 };
 
 @interface PLSPatcher ()
@@ -68,6 +71,7 @@ @interface PLSPatcher ()
 @property pfPatcher* patcher;
 @property NSTimer* networkPumpTimer;
 @property Patcher cppPatcher;
+@property NSURL* updatedClientURL;
 @end
 
 @implementation PLSPatcher
@@ -88,6 +92,7 @@ - (id)init
     _patcher->OnCompletion(std::bind(&Patcher::IOnPatchComplete, _cppPatcher, std::placeholders::_1,
                                      std::placeholders::_2));
     _patcher->OnFileDownloadDesired(IApproveDownload);
+    _patcher->OnSelfPatch(std::bind(&Patcher::ISelfPatch, _cppPatcher, std::placeholders::_1));
 
     self.networkPumpTimer = [NSTimer timerWithTimeInterval:1.0 / 1000.0
                                                    repeats:true
@@ -106,6 +111,35 @@ - (void)start
     self.patcher->Start();
 }
 
+- (NSURL *)completeSelfPatch
+{
+    NSString* destinationPath = [NSString stringWithSTString:plManifest::PatcherExecutable().AsString()];
+    NSURL *destinationURL = [NSURL fileURLWithPath:[NSString stringWithSTString:plManifest::PatcherExecutable().AsString()]];
+    
+    if ([NSFileManager.defaultManager fileExistsAtPath:destinationPath]) {
+        // need to swap
+        
+        char originalPath[PATH_MAX] = {0};
+        [self.updatedClientURL.path getFileSystemRepresentation:originalPath maxLength:sizeof(originalPath)];
+        
+        char newPath[PATH_MAX] = {0};
+        [destinationURL.path getFileSystemRepresentation:newPath maxLength:sizeof(newPath)];
+        
+        renamex_np(newPath, originalPath, RENAME_SWAP);
+        
+        // delete the old version - this is very likely us
+        // we want to terminate after. Our bundle will no longer be valid.
+        [NSFileManager.defaultManager removeItemAtURL:self.updatedClientURL error:nil];
+        return destinationURL;
+    } else {
+        // no executable already present! Just move things into place.
+        [NSFileManager.defaultManager moveItemAtURL:self.updatedClientURL toURL:destinationURL error:nil];
+        return destinationURL;
+    }
+    
+    return nil;
+}
+
 void Patcher::IOnDownloadBegin(const plFileName& file)
 {
     NSString* fileName = [NSString stringWithSTString:file.AsString()];
@@ -139,13 +173,103 @@ bool IApproveDownload(const plFileName& file)
     return extExcludeList.find(file.GetFileExt()) == extExcludeList.end();
 }
 
+static la_ssize_t copy_data(struct archive *ar, struct archive *aw)
+{
+  la_ssize_t r;
+  const void *buff;
+  size_t size;
+  la_int64_t offset;
+
+  for (;;) {
+    r = archive_read_data_block(ar, &buff, &size, &offset);
+    if (r == ARCHIVE_EOF)
+      return (ARCHIVE_OK);
+    if (r < ARCHIVE_OK)
+      return (r);
+    r = archive_write_data_block(aw, buff, size, offset);
+    if (r < ARCHIVE_OK) {
+      fprintf(stderr, "%s\n", archive_error_string(aw));
+      return (r);
+    }
+  }
+}
+
+void Patcher::ISelfPatch(const plFileName& file)
+{
+    struct archive *a;
+    struct archive *ext;
+    struct archive_entry *entry;
+    int flags;
+    la_ssize_t r;
+
+    /* Select which attributes we want to restore. */
+    flags = ARCHIVE_EXTRACT_TIME;
+    flags |= ARCHIVE_EXTRACT_PERM;
+    flags |= ARCHIVE_EXTRACT_ACL;
+    flags |= ARCHIVE_EXTRACT_FFLAGS;
+    
+    a = archive_read_new();
+    archive_read_support_format_all(a);
+    archive_read_support_filter_all(a);
+    ext = archive_write_disk_new();
+    archive_write_disk_set_options(ext, flags);
+    archive_write_disk_set_standard_lookup(ext);
+    if ((r = archive_read_open_filename(a, file.GetFileName().c_str(), 10240)))
+        exit(1);
+    
+    plFileSystem::Unlink(plManifest::PatcherExecutable());
+    
+    NSURL *tempDirectory = [NSFileManager.defaultManager URLForDirectory:NSItemReplacementDirectory inDomain:NSUserDomainMask appropriateForURL:[NSURL fileURLWithPath:NSFileManager.defaultManager.currentDirectoryPath] create:YES error:nil];
+    NSURL *outputURL = [tempDirectory URLByAppendingPathComponent:[NSString stringWithSTString:plManifest::PatcherExecutable().GetFileName()]];
+    [NSFileManager.defaultManager createDirectoryAtURL:outputURL withIntermediateDirectories:false attributes:nil error:nil];
+    ST::string outputPath = [outputURL.path STString];
+    
+    for (;;) {
+        r = archive_read_next_header(a, &entry);
+        if (r == ARCHIVE_EOF)
+            break;
+        if (r < ARCHIVE_OK)
+            fprintf(stderr, "%s\n", archive_error_string(a));
+        if (r < ARCHIVE_WARN)
+            exit(1);
+        const char* currentFile = archive_entry_pathname(entry);
+        auto fullOutputPath = outputPath + "/" + currentFile;
+        archive_entry_set_pathname(entry, fullOutputPath.c_str());
+        r = archive_write_header(ext, entry);
+        if (r < ARCHIVE_OK)
+            fprintf(stderr, "%s\n", archive_error_string(ext));
+        else if (archive_entry_size(entry) > 0) {
+            r = copy_data(a, ext);
+            if (r < ARCHIVE_OK)
+                fprintf(stderr, "%s\n", archive_error_string(ext));
+            if (r < ARCHIVE_WARN)
+                exit(1);
+        }
+        r = archive_write_finish_entry(ext);
+        if (r < ARCHIVE_OK)
+            fprintf(stderr, "%s\n", archive_error_string(ext));
+        if (r < ARCHIVE_WARN)
+            exit(1);
+    }
+    archive_read_close(a);
+    archive_read_free(a);
+    archive_write_close(ext);
+    archive_write_free(ext);
+    
+    plFileSystem::Unlink(file);
+    
+    PLSPatcher* patcher = parent;
+    parent.updatedClientURL = outputURL;
+}
+
 void Patcher::IOnPatchComplete(ENetError result, const ST::string& msg)
 {
     [parent.networkPumpTimer invalidate];
     if (IS_NET_SUCCESS(result)) {
         PLSPatcher* patcher = parent;
         dispatch_async(dispatch_get_main_queue(), ^{
-            [patcher.delegate patcherCompleted:patcher];
+            [patcher.delegate patcherCompleted:patcher
+                                  didSelfPatch:(patcher.updatedClientURL != nil)];
         });
     } else {
         NSString* msgString = [NSString stringWithSTString:msg];
diff --git a/Sources/Plasma/Apps/plClient/Mac-Cocoa/main.mm b/Sources/Plasma/Apps/plClient/Mac-Cocoa/main.mm
index 0101728f20..347c559eca 100644
--- a/Sources/Plasma/Apps/plClient/Mac-Cocoa/main.mm
+++ b/Sources/Plasma/Apps/plClient/Mac-Cocoa/main.mm
@@ -152,7 +152,8 @@ @interface AppDelegate : NSWindowController <NSApplicationDelegate,
     kArgStartUpAgeName,
     kArgPvdFile,
     kArgSkipIntroMovies,
-    kArgRenderer
+    kArgRenderer,
+    kArgNoSelfPatch
 };
 
 static const plCmdArgDef s_cmdLineArgs[] = {
@@ -166,6 +167,7 @@ @interface AppDelegate : NSWindowController <NSApplicationDelegate,
     { kCmdArgFlagged  | kCmdTypeString,     "PvdFile",         kArgPvdFile },
     { kCmdArgFlagged  | kCmdTypeBool,       "SkipIntroMovies", kArgSkipIntroMovies },
     { kCmdArgFlagged  | kCmdTypeString,     "Renderer",        kArgRenderer },
+    { kCmdArgFlagged  | kCmdTypeBool,       "NoSelfPatch",     kArgNoSelfPatch }
 };
 
 plCmdParser cmdParser(s_cmdLineArgs, std::size(s_cmdLineArgs));
@@ -353,7 +355,8 @@ - (void)applicationDidFinishLaunching:(NSNotification*)notification
     NetCommConnect();
     [[PLSServerStatus sharedStatus] loadServerStatus];
 
-    if (gDataServerLocal) {
+    BOOL didPatch = cmdParser.IsSpecified(kArgNoSelfPatch);
+    if (gDataServerLocal || didPatch) {
         [self initializeClient];
     } else {
         [self prepatch];
@@ -418,12 +421,25 @@ - (void)patcher:(PLSPatcher*)patcher beganDownloadOfFile:(NSString*)file
     [self.patcherWindow patcher:patcher beganDownloadOfFile:file];
 }
 
-- (void)patcherCompleted:(PLSPatcher*)patcher
+- (void)patcherCompleted:(PLSPatcher *)patcher didSelfPatch:(BOOL)selfPatched
 {
     self.patcher = nil;
     [NSApp endModalSession:self.currentModalSession];
     [self.patcherWindow.window close];
-    [self initializeClient];
+    if (selfPatched) {
+        NSURL* finalURL = [patcher completeSelfPatch];
+        
+        // Pass the "we've already patched" argument
+        NSArray* applicationArguments = [[[NSProcessInfo processInfo] arguments] arrayByAddingObject:@"-NoSelfPatch"];
+        
+        // no longer current, bye bye
+        [[NSWorkspace sharedWorkspace] launchApplicationAtURL:finalURL options:NSWorkspaceLaunchNewInstance configuration:@{NSWorkspaceLaunchConfigurationArguments: applicationArguments} error:nil];
+        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.3 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
+            [NSApp terminate:self];
+        });
+    } else {
+        [self initializeClient];
+    }
 }
 
 - (void)patcherCompletedWithError:(PLSPatcher*)patcher error:(NSError*)error
diff --git a/Sources/Plasma/CoreLib/plFileSystem.cpp b/Sources/Plasma/CoreLib/plFileSystem.cpp
index a4849b7c7f..d3de746b0d 100644
--- a/Sources/Plasma/CoreLib/plFileSystem.cpp
+++ b/Sources/Plasma/CoreLib/plFileSystem.cpp
@@ -84,6 +84,10 @@ You can contact Cyan Worlds, Inc. by email legal@cyan.com
 
 ST::string plFileName::GetFileName() const
 {
+    if(fName.ends_with("/"))
+    {
+        return plFileName(fName.before_last('/')).GetFileName();
+    }
     ST_ssize_t end = fName.find_last('/');
     if (end < 0)
         end = fName.find_last('\\');
diff --git a/Sources/Plasma/FeatureLib/pfPatcher/pfPatcher.cpp b/Sources/Plasma/FeatureLib/pfPatcher/pfPatcher.cpp
index c6171923d2..42bbb062f5 100644
--- a/Sources/Plasma/FeatureLib/pfPatcher/pfPatcher.cpp
+++ b/Sources/Plasma/FeatureLib/pfPatcher/pfPatcher.cpp
@@ -48,6 +48,7 @@ You can contact Cyan Worlds, Inc. by email legal@cyan.com
 
 #include "HeadSpin.h"
 #include "plFileSystem.h"
+#include "hsDarwin.h"
 #include "hsStream.h"
 #include "hsThread.h"
 #include "hsTimer.h"
@@ -99,10 +100,11 @@ enum FileFlags
 
     // Executable flags
     kRedistUpdate               = 1<<4,
+    kBundle                     = 1<<5,
 
     // Begin internal flags
-    kLastManifestFlag           = 1<<5,
-    kSelfPatch                  = 1<<6,
+    kLastManifestFlag           = 1<<6,
+    kSelfPatch                  = 1<<7,
 };
 
 // ===================================================
@@ -570,12 +572,50 @@ void pfPatcherWorker::IHashFile(pfPatcherQueuedFile& file)
     }
 
     // Check to see if ours matches
-    plFileInfo mine(file.fClientPath);
-    if (mine.FileSize() == file.fFileSize) {
-        plMD5Checksum cliMD5(file.fClientPath);
-        if (cliMD5 == file.fChecksum) {
-            WhitelistFile(file.fClientPath, false);
-            return;
+    if (file.fFlags & kBundle) {
+#if HS_BUILD_FOR_MACOS
+        // If this is a Mac app bundle, MD5 the executable. The executable will hold the
+        // code signing hash - and thus unique the entire bundle.
+        
+        CFURLRef bundleURL = CFURLCreateWithFileSystemPath(nullptr, CFStringCreateWithSTString(file.fClientPath.AsString()), kCFURLPOSIXPathStyle, true);
+        CFBundleRef bundle = CFBundleCreate(nullptr, bundleURL);
+        CFAutorelease(bundleURL);
+        
+        if (bundle) {
+            CFAutorelease(bundle);
+            
+            CFURLRef executableURL = CFBundleCopyExecutableURL(bundle);
+            
+            if (executableURL) {
+                // Ugh, CFBundleCopyExecutableURL returns a relative path from inside the app bundle.
+                // Sanitize.
+                CFURLRef fullExecutableURL = CFURLCreateFilePathURL(nullptr, executableURL, nullptr);
+                CFStringRef executablePath = CFURLCopyFileSystemPath(fullExecutableURL, kCFURLPOSIXPathStyle);
+                
+                plFileName path(STStringFromCFString(executablePath));
+                plMD5Checksum cliMD5(path);
+                
+                CFRelease(executablePath);
+                CFRelease(executableURL);
+                
+                if (cliMD5 == file.fChecksum) {
+                    WhitelistFile(file.fClientPath, false);
+                    return;
+                }
+            }
+        }
+#else
+        WhitelistFile(file.fClientPath, false);
+        return;
+#endif
+    } else {
+        plFileInfo mine(file.fClientPath);
+        if (mine.FileSize() == file.fFileSize) {
+            plMD5Checksum cliMD5(file.fClientPath);
+            if (cliMD5 == file.fChecksum) {
+                WhitelistFile(file.fClientPath, false);
+                return;
+            }
         }
     }
 
diff --git a/Sources/Plasma/FeatureLib/pfPatcher/plManifests.cpp b/Sources/Plasma/FeatureLib/pfPatcher/plManifests.cpp
index e6238497db..a27defc259 100644
--- a/Sources/Plasma/FeatureLib/pfPatcher/plManifests.cpp
+++ b/Sources/Plasma/FeatureLib/pfPatcher/plManifests.cpp
@@ -54,22 +54,38 @@ Mead, WA   99021
 
 plFileName plManifest::ClientExecutable()
 {
+#if HS_BUILD_FOR_MACOS
+    return MANIFEST("plClient.app", "UruExplorer.app");
+#else
     return MANIFEST("plClient.exe", "UruExplorer.exe");
+#endif
 }
 
 plFileName plManifest::PatcherExecutable()
 {
+#if HS_BUILD_FOR_MACOS
+    return MANIFEST("plClient.app", "UruExplorer.app");
+#else
     return MANIFEST("plUruLauncher.exe", "UruLauncher.exe");
+#endif
 }
 
 ST::string plManifest::ClientManifest()
 {
+#if HS_BUILD_FOR_MACOS
+    return MANIFEST("MacThinInternal", "MacThinExternal");
+#else
     return MANIFEST("ThinInternal", "ThinExternal");
+#endif
 }
 
 ST::string plManifest::ClientImageManifest()
 {
+#if HS_BUILD_FOR_MACOS
+    return MANIFEST("MacInternal", "MacExternal");
+#else
     return MANIFEST("Internal", "External");
+#endif
 }
 
 ST::string plManifest::PatcherManifest()
diff --git a/cmake/Findlibarchive.cmake b/cmake/Findlibarchive.cmake
new file mode 100644
index 0000000000..ce4282414c
--- /dev/null
+++ b/cmake/Findlibarchive.cmake
@@ -0,0 +1,43 @@
+include(FindPackageHandleStandardArgs)
+include(SelectLibraryConfigurations)
+
+find_path(libarchive_INCLUDE_DIR
+    NAMES archive.h
+)
+find_library(libarchive_LIBRARY_RELEASE NAMES archive libarchive)
+find_library(libarchive_LIBRARY_DEBUG NAMES archive libarchive)
+
+# Cope with vcpkg no longer renaming the debug library. This is needed due to MSVC's STL iterators
+# not being ABI compatible from debug to release mode.
+if(libwebm_LIBRARY_RELEASE AND NOT libwebm_LIBRARY_DEBUG)
+    foreach(prefix_path IN LISTS CMAKE_PREFIX_PATH)
+        if(prefix_path MATCHES "[Dd][Ee][Bb][Uu][Gg]\/?$")
+            list(APPEND _debug_paths "${prefix_path}")
+        endif()
+        if(_debug_paths)
+            find_library(libarchive_LIBRARY_DEBUG
+                NAMES archive libarchive archived libarchived
+                PATHS ${_debug_paths}
+                PATH_SUFFIXES lib
+                NO_CMAKE_PATH
+            )
+        endif()
+    endforeach()
+endif()
+
+select_library_configurations(libarchive)
+find_package_handle_standard_args(libarchive REQUIRED_VARS libarchive_INCLUDE_DIR libarchive_LIBRARY)
+
+if(libarchive_FOUND AND NOT TARGET libarchive::libarchive)
+    add_library(libarchive::libarchive IMPORTED UNKNOWN)
+    set_target_properties(libarchive::libarchive PROPERTIES INTERFACE_INCLUDE_DIRECTORIES ${libarchive_INCLUDE_DIR})
+    if(libarchive_LIBRARY_RELEASE AND libarchive_LIBRARY_DEBUG)
+        set_target_properties(
+            libarchive::libarchive PROPERTIES
+            IMPORTED_LOCATION_DEBUG ${libarchive_LIBRARY_DEBUG}
+            IMPORTED_LOCATION_RELEASE ${libarchive_LIBRARY_RELEASE}
+        )
+    else()
+        set_target_properties(libarchive::libarchive PROPERTIES IMPORTED_LOCATION ${libarchive_LIBRARY})
+    endif()
+endif()
diff --git a/vcpkg.json b/vcpkg.json
index ddfe06d95e..fd8bb61b09 100644
--- a/vcpkg.json
+++ b/vcpkg.json
@@ -11,6 +11,10 @@
         "platform": "!(osx | windows)"
       },
       "freetype",
+      {
+        "name": "libarchive",
+        "platform": "osx"
+      },
       "libepoxy",
       "libjpeg-turbo",
       "libogg",