diff --git a/Source/Headers/Project/XCTest/CDRXCTestSupport.h b/Source/Headers/Project/XCTest/CDRXCTestSupport.h
index 80e11d02..cd33e08a 100644
--- a/Source/Headers/Project/XCTest/CDRXCTestSupport.h
+++ b/Source/Headers/Project/XCTest/CDRXCTestSupport.h
@@ -22,8 +22,12 @@
 - (id)CDR_original_allTests;
 - (id)initWithName:(NSString *)aName;
 
-// XCTestObservationCenter
+@end
+
+@interface XCTestObservationCenter: NSObject
 + (instancetype)sharedTestObservationCenter;
 - (void)addTestObserver:(id<XCTestObservation>)observer;
-
+- (void)_addLegacyTestObserver:(id)observer;
+- (void)CDR_original_addTestObserver:(id<XCTestObservation>)observer;
+- (void)CDR_original__addLegacyTestObserver:(id)observer;
 @end
diff --git a/Source/XCTest/CDRXCTestFunctions.m b/Source/XCTest/CDRXCTestFunctions.m
index 4e74ecd3..51eb3a21 100644
--- a/Source/XCTest/CDRXCTestFunctions.m
+++ b/Source/XCTest/CDRXCTestFunctions.m
@@ -23,25 +23,19 @@ id CDRCreateXCTestSuite() {
     return [[[testSuiteSubclass alloc] initWithSpecRun:run] autorelease];
 }
 
-void CDRInjectIntoXCTestRunner() {
+void CDRAddCedarTestObserver(id observationCenter) {
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        [observationCenter CDR_original_addTestObserver:[[CDRXCTestObserver alloc] init]];
+    });
+}
+
+void CDRSwizzleTestSuiteAllTestsMethod() {
     Class testSuiteClass = NSClassFromString(@"XCTestSuite") ?: NSClassFromString(@"SenTestSuite");
     if (!testSuiteClass) {
         [[NSException exceptionWithName:@"CedarNoTestFrameworkAvailable" reason:@"You must link against either the XCTest or SenTestingKit frameworks." userInfo:nil] raise];
     }
 
-    // if possible, use the new XCTestObservation protocol available in Xcode 7
-    Class observationCenterClass = NSClassFromString(@"XCTestObservationCenter");
-    if (observationCenterClass && [observationCenterClass respondsToSelector:@selector(sharedTestObservationCenter)]) {
-        // Accessing the `sharedTestObservationCenter` too early causes XCTest console output to break when running
-        // on Xcode 7.3. Deferring adding the observer works around this issue. (rdar://25456276)
-        dispatch_async(dispatch_get_main_queue(), ^{
-            id observationCenter = [observationCenterClass sharedTestObservationCenter];
-            static CDRXCTestObserver *xcTestObserver;
-            xcTestObserver = [[CDRXCTestObserver alloc] init];
-            [observationCenter addTestObserver:xcTestObserver];
-        });
-    }
-
     Class testSuiteMetaClass = object_getClass(testSuiteClass);
     Method m = class_getClassMethod(testSuiteClass, @selector(allTests));
 
@@ -53,3 +47,36 @@ void CDRInjectIntoXCTestRunner() {
     });
     class_replaceMethod(testSuiteMetaClass, @selector(allTests), newImp, method_getTypeEncoding(m));
 }
+
+void CDRSwizzleTestObservationCenter() {
+    Class observationCenterClass = NSClassFromString(@"XCTestObservationCenter");
+    if (observationCenterClass && [observationCenterClass respondsToSelector:@selector(sharedTestObservationCenter)]) {
+        // Swizzle -addTestObserver:
+        Method addTestObserverMethod = class_getInstanceMethod(observationCenterClass, @selector(addTestObserver:));
+        class_addMethod(observationCenterClass, @selector(CDR_original_addTestObserver:), method_getImplementation(addTestObserverMethod), method_getTypeEncoding(addTestObserverMethod));
+
+        IMP newAddTestObserverImp = imp_implementationWithBlock(^void(id self, id observer){
+            [self CDR_original_addTestObserver:observer];
+            CDRAddCedarTestObserver(self);
+        });
+        class_replaceMethod(observationCenterClass, @selector(addTestObserver:), newAddTestObserverImp, method_getTypeEncoding(addTestObserverMethod));
+
+
+        // Swizzle -_addLegacyTestObserver:
+        Method addLegacyTestObserverMethod = class_getInstanceMethod(observationCenterClass, @selector(_addLegacyTestObserver:));
+        if (addLegacyTestObserverMethod) {
+            class_addMethod(observationCenterClass, @selector(CDR_original__addLegacyTestObserver:), method_getImplementation(addLegacyTestObserverMethod), method_getTypeEncoding(addLegacyTestObserverMethod));
+
+            IMP newAddLegacyTestObserverImp = imp_implementationWithBlock(^void(id self, id observer){
+                [self CDR_original__addLegacyTestObserver:observer];
+                CDRAddCedarTestObserver(self);
+            });
+            class_replaceMethod(observationCenterClass, @selector(_addLegacyTestObserver:), newAddLegacyTestObserverImp, method_getTypeEncoding(addLegacyTestObserverMethod));
+        }
+    }
+}
+
+void CDRInjectIntoXCTestRunner() {
+    CDRSwizzleTestSuiteAllTestsMethod();
+    CDRSwizzleTestObservationCenter();
+}
diff --git a/Spec/SpecBundle/SpecBundle-Info.plist b/Spec/SpecBundle/SpecBundle-Info.plist
index ba72822e..abca64a6 100644
--- a/Spec/SpecBundle/SpecBundle-Info.plist
+++ b/Spec/SpecBundle/SpecBundle-Info.plist
@@ -20,5 +20,7 @@
 	<string>????</string>
 	<key>CFBundleVersion</key>
 	<string>1</string>
+	<key>NSPrincipalClass</key>
+	<string>TestObservationHelper</string>
 </dict>
 </plist>
diff --git a/Spec/SpecBundle/Support/TestObservationHelper.m b/Spec/SpecBundle/Support/TestObservationHelper.m
index 428847bf..58122758 100644
--- a/Spec/SpecBundle/Support/TestObservationHelper.m
+++ b/Spec/SpecBundle/Support/TestObservationHelper.m
@@ -7,20 +7,21 @@ + (instancetype)defaultTestSuite;
 
 @interface TestObservationHelper () <XCTestObservation> @end
 
+// This class is loaded as the NSPrincipalClass of test bundles that require it, at which point
+// it registers itself as a test observer.
 @implementation TestObservationHelper
 
 static NSMutableArray *_knownTestSuites;
 
-+ (void)load {
-    Class observationCenterClass = NSClassFromString(@"XCTestObservationCenter");
-    if (observationCenterClass && [observationCenterClass respondsToSelector:@selector(sharedTestObservationCenter)]) {
-        _knownTestSuites = [NSMutableArray array];
-
-        // See comment in CDRXCTestFunctions.m for context on the dispatch_async
-        dispatch_async(dispatch_get_main_queue(), ^{
-            [[observationCenterClass sharedTestObservationCenter] addTestObserver:(id)[TestObservationHelper new]];
-        });
+- (instancetype)init {
+    if (self = [super init]) {
+        Class observationCenterClass = NSClassFromString(@"XCTestObservationCenter");
+        if (observationCenterClass && [observationCenterClass respondsToSelector:@selector(sharedTestObservationCenter)]) {
+            _knownTestSuites = [NSMutableArray array];
+            [[observationCenterClass sharedTestObservationCenter] addTestObserver:self];
+        }
     }
+    return self;
 }
 
 + (NSArray *)knownTestSuites {