diff --git a/Squirrel/SQRLDirectoryManager.h b/Squirrel/SQRLDirectoryManager.h
index 1b10ce2f..5b65f6e1 100644
--- a/Squirrel/SQRLDirectoryManager.h
+++ b/Squirrel/SQRLDirectoryManager.h
@@ -39,4 +39,14 @@
 // Returns a signal which synchronously sends a URL then completes, or errors.
 - (RACSignal *)shipItStateURL;
 
+// Determines where ShipIt's stdout log should be saved.
+//
+// Returns a signal which synchronously sends a URL then completes, or errors.
+- (RACSignal *)shipItStdoutURL;
+
+// Determines where ShipIt's stderr log should be saved.
+//
+// Returns a signal which synchronously sends a URL then completes, or errors.
+- (RACSignal *)shipItStderrURL;
+
 @end
diff --git a/Squirrel/SQRLDirectoryManager.m b/Squirrel/SQRLDirectoryManager.m
index e43b2a50..34f32107 100644
--- a/Squirrel/SQRLDirectoryManager.m
+++ b/Squirrel/SQRLDirectoryManager.m
@@ -75,6 +75,24 @@ - (RACSignal *)shipItStateURL {
 		setNameWithFormat:@"%@ -shipItStateURL", self];
 }
 
+- (RACSignal *)shipItStdoutURL {
+	return [[[self
+		storageURL]
+		map:^(NSURL *folderURL) {
+			return [folderURL URLByAppendingPathComponent:@"ShipIt_stdout.log"];
+		}]
+		setNameWithFormat:@"%@ -shipItStdoutURL", self];
+}
+
+- (RACSignal *)shipItStderrURL {
+	return [[[self
+		storageURL]
+		map:^(NSURL *folderURL) {
+			return [folderURL URLByAppendingPathComponent:@"ShipIt_stderr.log"];
+		}]
+		setNameWithFormat:@"%@ -shipItStderrURL", self];
+}
+
 #pragma mark NSObject
 
 - (NSString *)description {
diff --git a/Squirrel/SQRLShipItLauncher.m b/Squirrel/SQRLShipItLauncher.m
index 49c66c97..c39fca43 100644
--- a/Squirrel/SQRLShipItLauncher.m
+++ b/Squirrel/SQRLShipItLauncher.m
@@ -31,9 +31,9 @@ + (RACSignal *)shipItJobDictionary {
 	return [[[RACSignal
 		defer:^{
 			SQRLDirectoryManager *directoryManager = [[SQRLDirectoryManager alloc] initWithApplicationIdentifier:jobLabel];
-			return [directoryManager storageURL];
+			return [RACSignal zip:@[ [directoryManager shipItStdoutURL], [directoryManager shipItStderrURL] ]];
 		}]
-		map:^(NSURL *storageURL) {
+		reduceEach:^(NSURL *stdoutURL, NSURL *stderrURL) {
 			NSBundle *squirrelBundle = [NSBundle bundleForClass:self.class];
 			NSAssert(squirrelBundle != nil, @"Could not open Squirrel.framework bundle");
 
@@ -57,8 +57,8 @@ + (RACSignal *)shipItJobDictionary {
 			[arguments addObject:jobLabel];
 
 			jobDict[@(LAUNCH_JOBKEY_PROGRAMARGUMENTS)] = arguments;
-			jobDict[@(LAUNCH_JOBKEY_STANDARDOUTPATH)] = [storageURL URLByAppendingPathComponent:@"ShipIt_stdout.log"].path;
-			jobDict[@(LAUNCH_JOBKEY_STANDARDERRORPATH)] = [storageURL URLByAppendingPathComponent:@"ShipIt_stderr.log"].path;
+			jobDict[@(LAUNCH_JOBKEY_STANDARDOUTPATH)] = stdoutURL.path;
+			jobDict[@(LAUNCH_JOBKEY_STANDARDERRORPATH)] = stderrURL.path;
 
 			return jobDict;
 		}]
diff --git a/Squirrel/SQRLUpdater.m b/Squirrel/SQRLUpdater.m
index b9a8ed5c..57a094bb 100644
--- a/Squirrel/SQRLUpdater.m
+++ b/Squirrel/SQRLUpdater.m
@@ -171,13 +171,8 @@ - (id)initWithUpdateRequest:(NSURLRequest *)updateRequest {
 		NSMutableURLRequest *request = [self.updateRequest mutableCopy];
 		[request setValue:@"application/json" forHTTPHeaderField:@"Accept"];
 
-		// Prune old updates before the first update check.
-		return [[[[[[[[[self
-			pruneUpdateDirectories]
-			catch:^(NSError *error) {
-				NSLog(@"Error pruning old updates: %@", error);
-				return [RACSignal empty];
-			}]
+		return [[[[[[[[self
+			performHousekeeping]
 			then:^{
 				self.state = SQRLUpdaterStateCheckingForUpdate;
 
@@ -480,6 +475,15 @@ - (RACSignal *)shipItStateURL {
 		setNameWithFormat:@"%@ -shipItStateURL", self];
 }
 
+- (RACSignal *)performHousekeeping {
+	return [[RACSignal
+		merge:@[ [self pruneUpdateDirectories], [self truncateLogs] ]]
+		catch:^(NSError *error) {
+			NSLog(@"Error doing housekeeping: %@", error);
+			return [RACSignal empty];
+		}];
+}
+
 /// Lazily removes outdated temporary directories (used for previous updates)
 /// upon subscription.
 ///
@@ -516,6 +520,39 @@ - (RACSignal *)pruneUpdateDirectories {
 		setNameWithFormat:@"%@ -prunedUpdateDirectories", self];
 }
 
+
+// Like truncation, but backwards.
+- (RACSignal *)backwardTruncateFile:(NSURL *)fileURL {
+	return [RACSignal defer:^{
+		static const NSInteger MAX_LENGTH = 1024 * 1024 * 8;
+
+		NSError *error;
+		NSFileHandle *handle = [NSFileHandle fileHandleForWritingToURL:fileURL error:&error];
+		if (handle == nil) return [RACSignal error:error];
+
+		unsigned long long fileLength = [handle seekToEndOfFile];
+		if (fileLength <= MAX_LENGTH) return [RACSignal empty];
+
+		[handle seekToFileOffset:fileLength - MAX_LENGTH];
+		NSData *mostRecentData = [handle readDataToEndOfFile];
+		[handle truncateFileAtOffset:0];
+		[handle writeData:mostRecentData];
+
+		return [RACSignal empty];
+	}];
+}
+
+- (RACSignal *)truncateLogs {
+	return [[RACSignal
+		defer:^{
+			SQRLDirectoryManager *directoryManager = [[SQRLDirectoryManager alloc] initWithApplicationIdentifier:SQRLShipItLauncher.shipItJobLabel];
+			return [RACSignal zip:@[ [directoryManager shipItStdoutURL], [directoryManager shipItStderrURL] ]];
+		}]
+		reduceEach:^(NSURL *stdoutURL, NSURL *stderrURL) {
+			return [RACSignal merge:@[ [self backwardTruncateFile:stdoutURL], [self backwardTruncateFile:stderrURL] ]];
+		}];
+}
+
 #pragma mark Installing Updates
 
 - (RACSignal *)verifyAndPrepareUpdate:(SQRLUpdate *)update fromBundle:(NSBundle *)updateBundle {