diff --git a/Squirrel/SQRLUpdater.m b/Squirrel/SQRLUpdater.m
index 2c860bb1..51b4deae 100644
--- a/Squirrel/SQRLUpdater.m
+++ b/Squirrel/SQRLUpdater.m
@@ -6,6 +6,7 @@
 //  Copyright (c) 2013 GitHub. All rights reserved.
 //
 
+#import <sys/xattr.h>
 #import "SQRLUpdater.h"
 #import "NSBundle+SQRLVersionExtensions.h"
 #import "NSError+SQRLVerbosityExtensions.h"
@@ -53,6 +54,10 @@ @interface SQRLUpdater ()
 // Sends completed or error.
 @property (nonatomic, strong, readonly) RACSignal *shipItLauncher;
 
+/// Was the app quarantined when we tried checking for updates? Will be nil if
+/// we haven't checked yet.
+@property (atomic, copy) NSNumber *wasQuarantined;
+
 // Parses an update model from downloaded data.
 //
 // data - JSON data representing an update manifest. This must not be nil.
@@ -171,9 +176,16 @@ - (id)initWithUpdateRequest:(NSURLRequest *)updateRequest {
 		NSMutableURLRequest *request = [self.updateRequest mutableCopy];
 		[request setValue:@"application/json" forHTTPHeaderField:@"Accept"];
 
-		return [[[[[[[[self
+		return [[[[[[[[[self
 			performHousekeeping]
 			then:^{
+				return [self unquarantineApp];
+			}]
+			flattenMap:^(NSNumber *quarantined) {
+				// If we were quarantined then we can't check for updates until
+				// the app is relaunched.
+				if (quarantined.boolValue) return [RACSignal empty];
+
 				self.state = SQRLUpdaterStateCheckingForUpdate;
 
 				return [NSURLConnection rac_sendAsynchronousRequest:request];
@@ -240,6 +252,21 @@ - (id)initWithUpdateRequest:(NSURLRequest *)updateRequest {
 
 #pragma mark Checking for Updates
 
+- (RACSignal *)unquarantineApp {
+	return [RACSignal createSignal:^ RACDisposable * (id<RACSubscriber> subscriber) {
+		if (self.wasQuarantined == nil) {
+			NSURL *targetURL = NSRunningApplication.currentApplication.bundleURL;
+			const char *path = targetURL.path.fileSystemRepresentation;
+			int result = removexattr(path, "com.apple.quarantine", XATTR_NOFOLLOW);
+			self.wasQuarantined = @(result == 0);
+		}
+
+		[subscriber sendNext:self.wasQuarantined];
+		[subscriber sendCompleted];
+		return nil;
+	}];
+}
+
 - (RACDisposable *)startAutomaticChecksWithInterval:(NSTimeInterval)interval {
 	@weakify(self);