diff --git a/Autoupdate/SPUMessageTypes.h b/Autoupdate/SPUMessageTypes.h
index 8b69a006b5..0a48bd0724 100644
--- a/Autoupdate/SPUMessageTypes.h
+++ b/Autoupdate/SPUMessageTypes.h
@@ -10,10 +10,6 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-@class SUHost;
-
-extern NSString *SPUAppcastItemArchiveKey;
-
 // Order matters; higher stages have higher values.
 typedef NS_ENUM(int32_t, SPUInstallerMessageType)
 {
@@ -40,10 +36,13 @@ typedef NS_ENUM(int32_t, SPUUpdaterMessageType)
 
 BOOL SPUInstallerMessageTypeIsLegal(SPUInstallerMessageType oldMessageType, SPUInstallerMessageType newMessageType);
 
+// Used by framework to communicate to installer (Autoupdate)
 NSString *SPUInstallerServiceNameForBundleIdentifier(NSString *bundleIdentifier);
 
+// Used by framework to communicate to progress agent tool (Updater)
 NSString *SPUStatusInfoServiceNameForBundleIdentifier(NSString *bundleIdentifier);
 
+// Used by progress agent tool to communicate to installer (Autoupdate)
 NSString *SPUProgressAgentServiceNameForBundleIdentifier(NSString *bundleIdentifier);
 
 NS_ASSUME_NONNULL_END
diff --git a/Autoupdate/SPUMessageTypes.m b/Autoupdate/SPUMessageTypes.m
index 4ea84ac3b2..132b3d975e 100644
--- a/Autoupdate/SPUMessageTypes.m
+++ b/Autoupdate/SPUMessageTypes.m
@@ -7,24 +7,19 @@
 //
 
 #import "SPUMessageTypes.h"
-#import "SUHost.h"
 
 
 #include "AppKitPrevention.h"
 
-NSString *SPUAppcastItemArchiveKey = @"SPUAppcastItemArchive";
-
 // Tags added to the bundle identifier which is used as Mach service names
-// These should be very short because length restrictions exist on earlier versions of macOS
+// These should be very short because of length restrictions
 #define SPARKLE_INSTALLER_TAG @"-spki"
 #define SPARKLE_STATUS_TAG @"-spks"
 #define SPARKLE_PROGRESS_TAG @"-spkp"
-#define SPARKLE_PROGRESS_LAUNCH_INSTALLER_TAG @"-spkl"
 
-// macOS 10.8 at least can't handle service names that are 64 characters or longer
-// This was fixed some point after 10.8, but I'm not sure if it was fixed in 10.9 or 10.10 or 10.11
-// If we knew when it was fixed, this could only be relevant to OS versions prior to that
-#define MAX_SERVICE_NAME_LENGTH 63u
+// macOS 10.8 couldn't handle service names that are >= 64 characters,
+// but 10.9 raised this to >= 128 characters
+#define MAX_SERVICE_NAME_LENGTH 127u
 
 BOOL SPUInstallerMessageTypeIsLegal(SPUInstallerMessageType oldMessageType, SPUInstallerMessageType newMessageType)
 {