diff --git a/Bugsnag.xcodeproj/project.pbxproj b/Bugsnag.xcodeproj/project.pbxproj
index b12137810..75084415f 100644
--- a/Bugsnag.xcodeproj/project.pbxproj
+++ b/Bugsnag.xcodeproj/project.pbxproj
@@ -985,6 +985,7 @@
 		79659E151A0AFFF800280978 /* Debug */ = {
 			isa = XCBuildConfiguration;
 			buildSettings = {
+				CLANG_ALLOW_NON_MODULAR_INCLUDES_IN_FRAMEWORK_MODULES = YES;
 				CODE_SIGN_IDENTITY = "Developer ID Application";
 				"CODE_SIGN_IDENTITY[sdk=iphoneos*]" = "Developer ID Application";
 				CONFIGURATION_BUILD_DIR = "$(BUILD_DIR)/$(CONFIGURATION)";
@@ -994,6 +995,7 @@
 		79659E161A0AFFF800280978 /* Release */ = {
 			isa = XCBuildConfiguration;
 			buildSettings = {
+				CLANG_ALLOW_NON_MODULAR_INCLUDES_IN_FRAMEWORK_MODULES = YES;
 				CODE_SIGN_IDENTITY = "Developer ID Application";
 				CONFIGURATION_BUILD_DIR = "$(BUILD_DIR)/$(CONFIGURATION)";
 			};
diff --git a/Source/Bugsnag/BugsnagConfiguration.h b/Source/Bugsnag/BugsnagConfiguration.h
index b42398079..1c44614fb 100644
--- a/Source/Bugsnag/BugsnagConfiguration.h
+++ b/Source/Bugsnag/BugsnagConfiguration.h
@@ -27,6 +27,7 @@
 #import <Foundation/Foundation.h>
 
 #import "BugsnagMetaData.h"
+#import "KSCrashReportWriter.h"
 
 @class BugsnagBreadcrumbs;
 
@@ -41,6 +42,7 @@
 @property(nonatomic,readwrite,retain) BugsnagMetaData* metaData;
 @property(nonatomic,readwrite,retain) BugsnagMetaData* config;
 @property(nonatomic,readonly,strong) BugsnagBreadcrumbs* breadcrumbs;
+@property(nonatomic) void (*onCrashHandler)(const KSCrashReportWriter* writer);
 
 @property(nonatomic) BOOL autoNotify;
 
diff --git a/Source/Bugsnag/BugsnagNotifier.m b/Source/Bugsnag/BugsnagNotifier.m
index 2889f39fc..597bb5b82 100644
--- a/Source/Bugsnag/BugsnagNotifier.m
+++ b/Source/Bugsnag/BugsnagNotifier.m
@@ -52,6 +52,8 @@
     char *configJSON;
     // Contains notifier state, under "deviceState" and crash-specific information under "crash".
     char *stateJSON;
+    // User onCrash handler
+    void (*onCrash)(const KSCrashReportWriter* writer);
 };
 
 static struct bugsnag_data_t g_bugsnag_data;
@@ -72,6 +74,9 @@ void BSSerializeDataCrashHandler(const KSCrashReportWriter *writer) {
     if (g_bugsnag_data.stateJSON) {
         writer->addJSONElement(writer, "state", g_bugsnag_data.stateJSON);
     }
+    if (g_bugsnag_data.onCrash) {
+        g_bugsnag_data.onCrash(writer);
+    }
 }
 
 /**
@@ -117,6 +122,7 @@ - (id) initWithConfiguration:(BugsnagConfiguration*) initConfiguration {
         [self metaDataChanged: self.configuration.metaData];
         [self metaDataChanged: self.configuration.config];
         [self metaDataChanged: self.state];
+        g_bugsnag_data.onCrash = self.configuration.onCrashHandler;
     }
 
     return self;
diff --git a/docs/Configuration.md b/docs/Configuration.md
index 9287e7fdd..013019c86 100644
--- a/docs/Configuration.md
+++ b/docs/Configuration.md
@@ -67,6 +67,28 @@ config.apiKey = @"YOUR_API_KEY_HERE";
 [Bugsnag startBugsnagWithConfiguration: config];
 ```
 
+### `onCrashHandler`
+
+When a crash occurs in an application, information about the runtime state of
+the application is collected and prepared to be sent to Bugsnag on the next
+launch. The `onCrashHandler` hook allows you to execute additional code after
+the crash report has been written.
+
+**NOTE:** All functions called from a signal handler must be
+[asynchronous-safe](https://www.securecoding.cert.org/confluence/display/c/SIG30-C.+Call+only+asynchronous-safe+functions+within+signal+handlers).
+This excludes any Objective-C, in particular.
+
+```objective-c
+void HandleCrashedThread(const KSCrashReportWriter *writer) {
+  // possibly serialize data, call another crash reporter
+}
+
+// ...
+
+BugsnagConfiguration *config = [[BugsnagConfiguration alloc] init];
+config.onCrashHandler = &HandleCrashedThread;
+```
+
 ### `releaseStage`
 
 In order to distinguish between errors that occur in different stages of the