diff --git a/Sources/CNIODarwin/include/CNIODarwin.h b/Sources/CNIODarwin/include/CNIODarwin.h
index e096763956..6fbec9eb6e 100644
--- a/Sources/CNIODarwin/include/CNIODarwin.h
+++ b/Sources/CNIODarwin/include/CNIODarwin.h
@@ -18,8 +18,6 @@
 #include <sys/socket.h>
 #include <time.h>
 
-#include <netinet/ip.h>
-
 // Darwin platforms do not have a sendmmsg implementation available to them. This C module
 // provides a shim that implements sendmmsg on top of sendmsg. It also provides a shim for
 // recvmmsg, but does not actually implement that shim, instantly throwing errors if called.
@@ -33,6 +31,12 @@ typedef struct {
     unsigned int msg_len;
 } CNIODarwin_mmsghdr;
 
+extern int CNIODarwin_IPTOS_ECN_NOTECT;
+extern int CNIODarwin_IPTOS_ECN_MASK;
+extern int CNIODarwin_IPTOS_ECN_ECT0;
+extern int CNIODarwin_IPTOS_ECN_ECT1;
+extern int CNIODarwin_IPTOS_ECN_CE;
+
 int CNIODarwin_sendmmsg(int sockfd, CNIODarwin_mmsghdr *msgvec, unsigned int vlen, int flags);
 int CNIODarwin_recvmmsg(int sockfd, CNIODarwin_mmsghdr *msgvec, unsigned int vlen, int flags, struct timespec *timeout);
 
diff --git a/Sources/CNIODarwin/shim.c b/Sources/CNIODarwin/shim.c
index a77a380e59..6db2ee223f 100644
--- a/Sources/CNIODarwin/shim.c
+++ b/Sources/CNIODarwin/shim.c
@@ -19,6 +19,7 @@
 #include <limits.h>
 #include <errno.h>
 #include <assert.h>
+#include <netinet/ip.h>
 
 int CNIODarwin_sendmmsg(int sockfd, CNIODarwin_mmsghdr *msgvec, unsigned int vlen, int flags) {
     // Some quick error checking. If vlen can't fit into int, we bail.
@@ -80,4 +81,10 @@ size_t CNIODarwin_CMSG_SPACE(size_t payloadSizeBytes) {
     return CMSG_SPACE(payloadSizeBytes);
 }
 
+int CNIODarwin_IPTOS_ECN_NOTECT = IPTOS_ECN_NOTECT;
+int CNIODarwin_IPTOS_ECN_MASK = IPTOS_ECN_MASK;
+int CNIODarwin_IPTOS_ECN_ECT0 = IPTOS_ECN_ECT0;
+int CNIODarwin_IPTOS_ECN_ECT1 = IPTOS_ECN_ECT1;
+int CNIODarwin_IPTOS_ECN_CE = IPTOS_ECN_CE;
+
 #endif  // __APPLE__
diff --git a/Sources/NIO/ControlMessage.swift b/Sources/NIO/ControlMessage.swift
index 2869ec592c..6ec87d5681 100644
--- a/Sources/NIO/ControlMessage.swift
+++ b/Sources/NIO/ControlMessage.swift
@@ -191,12 +191,12 @@ struct ControlMessageParser {
 extension NIOExplicitCongestionNotificationState {
     /// Initialise a NIOExplicitCongestionNotificationState from a value received via either TCLASS or TOS cmsg.
     init(receivedValue: CInt) {
-        switch receivedValue & IPTOS_ECN_MASK {
-        case IPTOS_ECN_ECT1:
+        switch receivedValue & Posix.IPTOS_ECN_MASK {
+        case Posix.IPTOS_ECN_ECT1:
             self = .transportCapableFlag1
-        case IPTOS_ECN_ECT0:
+        case Posix.IPTOS_ECN_ECT0:
             self = .transportCapableFlag0
-        case IPTOS_ECN_CE:
+        case Posix.IPTOS_ECN_CE:
             self = .congestionExperienced
         default:
             self = .transportNotCapable
@@ -205,23 +205,17 @@ extension NIOExplicitCongestionNotificationState {
 }
 
 extension CInt {
-    #if os(macOS) || os(iOS) || os(watchOS) || os(tvOS)
-    private static let notCapableValue = IPTOS_ECN_NOTECT
-    #else
-    private static let notCapableValue = IPTOS_ECN_NOT_ECT    // Linux
-    #endif
-
     /// Create a CInt encoding of ExplicitCongestionNotification suitable for sending in TCLASS or TOS cmsg.
     init(ecnValue: NIOExplicitCongestionNotificationState) {
         switch ecnValue {
         case .transportNotCapable:
-            self = CInt.notCapableValue
+            self = Posix.IPTOS_ECN_NOTECT
         case .transportCapableFlag0:
-            self = IPTOS_ECN_ECT0
+            self = Posix.IPTOS_ECN_ECT0
         case .transportCapableFlag1:
-            self = IPTOS_ECN_ECT1
+            self = Posix.IPTOS_ECN_ECT1
         case .congestionExperienced:
-            self = IPTOS_ECN_CE
+            self = Posix.IPTOS_ECN_CE
         }
     }
 }
diff --git a/Sources/NIO/System.swift b/Sources/NIO/System.swift
index 7c8d01d712..008fe572e3 100644
--- a/Sources/NIO/System.swift
+++ b/Sources/NIO/System.swift
@@ -191,12 +191,22 @@ internal enum Posix {
     static let SHUT_RD: CInt = CInt(Darwin.SHUT_RD)
     static let SHUT_WR: CInt = CInt(Darwin.SHUT_WR)
     static let SHUT_RDWR: CInt = CInt(Darwin.SHUT_RDWR)
+    static let IPTOS_ECN_NOTECT: CInt = CNIODarwin_IPTOS_ECN_NOTECT
+    static let IPTOS_ECN_MASK: CInt = CNIODarwin_IPTOS_ECN_MASK
+    static let IPTOS_ECN_ECT0: CInt = CNIODarwin_IPTOS_ECN_ECT0
+    static let IPTOS_ECN_ECT1: CInt = CNIODarwin_IPTOS_ECN_ECT1
+    static let IPTOS_ECN_CE: CInt = CNIODarwin_IPTOS_ECN_CE
 #elseif os(Linux) || os(FreeBSD) || os(Android)
 
     static let UIO_MAXIOV: Int = Int(Glibc.UIO_MAXIOV)
     static let SHUT_RD: CInt = CInt(Glibc.SHUT_RD)
     static let SHUT_WR: CInt = CInt(Glibc.SHUT_WR)
     static let SHUT_RDWR: CInt = CInt(Glibc.SHUT_RDWR)
+    static let IPTOS_ECN_NOTECT: CInt = CInt(CNIOLinux.IPTOS_ECN_NOT_ECT)
+    static let IPTOS_ECN_MASK: CInt = CInt(CNIOLinux.IPTOS_ECN_MASK)
+    static let IPTOS_ECN_ECT0: CInt = CInt(CNIOLinux.IPTOS_ECN_ECT0)
+    static let IPTOS_ECN_ECT1: CInt = CInt(CNIOLinux.IPTOS_ECN_ECT1)
+    static let IPTOS_ECN_CE: CInt = CInt(CNIOLinux.IPTOS_ECN_CE)
 #else
     static var UIO_MAXIOV: Int {
         fatalError("unsupported OS")