diff --git a/OpenVPN Adapter/OpenVPNCertificate.h b/OpenVPN Adapter/OpenVPNCertificate.h
index 4cbb7bd..fb1c7f1 100644
--- a/OpenVPN Adapter/OpenVPNCertificate.h	
+++ b/OpenVPN Adapter/OpenVPNCertificate.h	
@@ -11,14 +11,14 @@
 @interface OpenVPNCertificate : NSObject
 
 + (nullable OpenVPNCertificate *)certificateWithPEM:(nonnull NSData *)pemData
-                                              error:(out NSError * __nullable * __nullable)error;
+                                              error:(out NSError * _Nullable * _Nullable)error;
 
 + (nullable OpenVPNCertificate *)certificateWithDER:(nonnull NSData *)derData
-                                              error:(out NSError * __nullable * __nullable)error;
+                                              error:(out NSError * _Nullable * _Nullable)error;
 
-- (nonnull instancetype) __unavailable init;
+- (nonnull instancetype) init NS_UNAVAILABLE;
 
-- (nullable NSData *)pemData:(out NSError * __nullable * __nullable)error;
-- (nullable NSData *)derData:(out NSError * __nullable * __nullable)error;
+- (nullable NSData *)pemData:(out NSError * _Nullable * _Nullable)error;
+- (nullable NSData *)derData:(out NSError * _Nullable * _Nullable)error;
 
 @end
diff --git a/OpenVPN Adapter/OpenVPNCertificate.m b/OpenVPN Adapter/OpenVPNCertificate.m
index f0c70f7..826792e 100644
--- a/OpenVPN Adapter/OpenVPNCertificate.m	
+++ b/OpenVPN Adapter/OpenVPNCertificate.m	
@@ -7,8 +7,8 @@
 //
 #import "OpenVPNCertificate.h"
 
-#import <mbedtls/x509_crt.h>
-#import <mbedtls/pem.h>
+#include <mbedtls/x509_crt.h>
+#include <mbedtls/pem.h>
 
 #import "NSError+OpenVPNError.h"
 
@@ -20,16 +20,6 @@
 
 @implementation OpenVPNCertificate
 
-- (instancetype)init
-{
-    self = [super init];
-    if (self) {
-        self.crt = malloc(sizeof(mbedtls_x509_crt));
-        mbedtls_x509_crt_init(self.crt);
-    }
-    return self;
-}
-
 + (OpenVPNCertificate *)certificateWithPEM:(NSData *)pemData error:(out NSError **)error {
     OpenVPNCertificate *certificate = [OpenVPNCertificate new];
     
@@ -62,6 +52,15 @@
     return certificate;
 }
 
+- (instancetype)init
+{
+    if (self = [super init]) {
+        _crt = malloc(sizeof(mbedtls_x509_crt));
+        mbedtls_x509_crt_init(_crt);
+    }
+    return self;
+}
+
 - (NSData *)pemData:(out NSError **)error {
     NSString *header = @"-----BEGIN CERTIFICATE-----\n";
     NSString *footer = @"-----END CERTIFICATE-----\n";
@@ -102,8 +101,8 @@
 }
 
 - (void)dealloc {
-    mbedtls_x509_crt_free(self.crt);
-    free(self.crt);
+    mbedtls_x509_crt_free(_crt);
+    free(_crt);
 }
 
 @end
diff --git a/OpenVPN Adapter/OpenVPNPrivateKey.h b/OpenVPN Adapter/OpenVPNPrivateKey.h
index 81ca5f6..61f8727 100644
--- a/OpenVPN Adapter/OpenVPNPrivateKey.h	
+++ b/OpenVPN Adapter/OpenVPNPrivateKey.h	
@@ -8,24 +8,24 @@
 
 #import <Foundation/Foundation.h>
 
-#import "OpenVPNKeyType.h"
+typedef NS_ENUM(NSInteger, OpenVPNKeyType);
 
 @interface OpenVPNPrivateKey : NSObject
 
 + (nullable OpenVPNPrivateKey *)keyWithPEM:(nonnull NSData *)pemData
                                   password:(nullable NSString *)password
-                                     error:(out NSError * __nullable * __nullable)error;
+                                     error:(out NSError * _Nullable * _Nullable)error;
 
 + (nullable OpenVPNPrivateKey *)keyWithDER:(nonnull NSData *)derData
                                   password:(nullable NSString *)password
-                                     error:(out NSError * __nullable * __nullable)error;
+                                     error:(out NSError * _Nullable * _Nullable)error;
 
-- (nonnull instancetype) __unavailable init;
+- (nonnull instancetype) init NS_UNAVAILABLE;
 
 @property (nonatomic, readonly) NSInteger size;
 @property (nonatomic, readonly) OpenVPNKeyType type;
 
-- (nullable NSData *)pemData:(out NSError * __nullable * __nullable)error;
-- (nullable NSData *)derData:(out NSError * __nullable * __nullable)error;
+- (nullable NSData *)pemData:(out NSError * _Nullable * _Nullable)error;
+- (nullable NSData *)derData:(out NSError * _Nullable * _Nullable)error;
 
 @end
diff --git a/OpenVPN Adapter/OpenVPNPrivateKey.m b/OpenVPN Adapter/OpenVPNPrivateKey.m
index deb4a6a..a941878 100644
--- a/OpenVPN Adapter/OpenVPNPrivateKey.m	
+++ b/OpenVPN Adapter/OpenVPNPrivateKey.m	
@@ -8,8 +8,9 @@
 
 #import "OpenVPNPrivateKey.h"
 
-#import <mbedtls/pk.h>
+#include <mbedtls/pk.h>
 
+#import "OpenVPNKeyType.h"
 #import "NSError+OpenVPNError.h"
 
 @interface OpenVPNPrivateKey ()
@@ -20,23 +21,6 @@
 
 @implementation OpenVPNPrivateKey
 
-- (instancetype)init {
-    self = [super init];
-    if (self) {
-        self.ctx = malloc(sizeof(mbedtls_pk_context));
-        mbedtls_pk_init(self.ctx);
-    }
-    return self;
-}
-
-- (NSInteger)size {
-    return mbedtls_pk_get_bitlen(self.ctx);
-}
-
-- (OpenVPNKeyType)type {
-    return (OpenVPNKeyType)mbedtls_pk_get_type(self.ctx);
-}
-
 + (nullable OpenVPNPrivateKey *)keyWithPEM:(NSData *)pemData password:(NSString *)password error:(out NSError **)error {
     OpenVPNPrivateKey *key = [OpenVPNPrivateKey new];
     
@@ -78,6 +62,22 @@
     return key;
 }
 
+- (instancetype)init {
+    if (self = [super init]) {
+        _ctx = malloc(sizeof(mbedtls_pk_context));
+        mbedtls_pk_init(_ctx);
+    }
+    return self;
+}
+
+- (NSInteger)size {
+    return mbedtls_pk_get_bitlen(self.ctx);
+}
+
+- (OpenVPNKeyType)type {
+    return (OpenVPNKeyType)mbedtls_pk_get_type(self.ctx);
+}
+
 - (NSData *)pemData:(out NSError **)error {
     size_t buffer_length = mbedtls_pk_get_len(self.ctx) * 10;
     unsigned char *pem_buffer = malloc(buffer_length);
@@ -123,8 +123,8 @@
 }
 
 - (void)dealloc {
-    mbedtls_pk_free(self.ctx);
-    free(self.ctx);
+    mbedtls_pk_free(_ctx);
+    free(_ctx);
 }
 
 @end
diff --git a/OpenVPN Adapter/OpenVPNReachability+Internal.h b/OpenVPN Adapter/OpenVPNReachability+Internal.h
index d38837a..a13c3bd 100644
--- a/OpenVPN Adapter/OpenVPNReachability+Internal.h	
+++ b/OpenVPN Adapter/OpenVPNReachability+Internal.h	
@@ -6,7 +6,6 @@
 //
 //
 
-#import "OpenVPNReachabilityTracker.h"
 #import "OpenVPNReachability.h"
 
 @interface OpenVPNReachability (Internal)
diff --git a/OpenVPN Adapter/OpenVPNReachability.h b/OpenVPN Adapter/OpenVPNReachability.h
index 8ba4632..123982d 100644
--- a/OpenVPN Adapter/OpenVPNReachability.h	
+++ b/OpenVPN Adapter/OpenVPNReachability.h	
@@ -7,7 +7,8 @@
 //
 
 #import <Foundation/Foundation.h>
-#import "OpenVPNReachabilityStatus.h"
+
+typedef NS_ENUM(NSInteger, OpenVPNReachabilityStatus);
 
 @interface OpenVPNReachability : NSObject
 
diff --git a/OpenVPN Adapter/OpenVPNReachability.mm b/OpenVPN Adapter/OpenVPNReachability.mm
index 360da7b..02d8383 100644
--- a/OpenVPN Adapter/OpenVPNReachability.mm	
+++ b/OpenVPN Adapter/OpenVPNReachability.mm	
@@ -6,11 +6,14 @@
 //
 //
 
-#import <openvpn/apple/reachable.hpp>
-
 #import "OpenVPNReachability.h"
 #import "OpenVPNReachability+Internal.h"
 
+#include <openvpn/apple/reachable.hpp>
+
+#import "OpenVPNReachabilityTracker.h"
+#import "OpenVPNReachabilityStatus.h"
+
 @interface OpenVPNReachability () {
     BOOL _isTracking;
 }
@@ -45,13 +48,12 @@
     }
 }
 
-- (nonnull instancetype)init {
-    self = [super init];
-    if (self) {
+- (instancetype)init {
+    if (self = [super init]) {
         _isTracking = NO;
 
-        self.tracker = new OpenVPNReachabilityTracker(true, false, (__bridge void *)self);
-        self.reachability = new Reachability(true, true);
+        _tracker = new OpenVPNReachabilityTracker(true, false, (__bridge void *)self);
+        _reachability = new Reachability(true, true);
     }
     return self;
 }
@@ -77,8 +79,8 @@
 }
 
 - (void)dealloc {
-    delete self.tracker;
-    delete self.reachability;
+    delete _tracker;
+    delete _reachability;
 }
 
 @end
diff --git a/OpenVPN Adapter/OpenVPNReachabilityTracker.h b/OpenVPN Adapter/OpenVPNReachabilityTracker.h
index 6ac0982..da61403 100644
--- a/OpenVPN Adapter/OpenVPNReachabilityTracker.h	
+++ b/OpenVPN Adapter/OpenVPNReachabilityTracker.h	
@@ -6,7 +6,7 @@
 //
 //
 
-#import <openvpn/apple/reachable.hpp>
+#include <openvpn/apple/reachable.hpp>
 
 using namespace openvpn;
 
diff --git a/OpenVPN Adapter/OpenVPNReachabilityTracker.mm b/OpenVPN Adapter/OpenVPNReachabilityTracker.mm
index a84cb38..68b4f2f 100644
--- a/OpenVPN Adapter/OpenVPNReachabilityTracker.mm	
+++ b/OpenVPN Adapter/OpenVPNReachabilityTracker.mm	
@@ -6,10 +6,13 @@
 //
 //
 
-#import "OpenVPNReachability+Internal.h"
 #import "OpenVPNReachabilityTracker.h"
 
-OpenVPNReachabilityTracker::OpenVPNReachabilityTracker(const bool enable_internet, const bool enable_wifi, void* handler) : ReachabilityTracker(enable_internet, enable_wifi) {
+#import "OpenVPNReachability+Internal.h"
+
+OpenVPNReachabilityTracker::OpenVPNReachabilityTracker(const bool enable_internet, const bool enable_wifi, void* handler) :
+    ReachabilityTracker(enable_internet, enable_wifi)
+{
     this->handler = handler;
 }