diff --git a/Sources/NetService/FoundationCompat.swift b/Sources/NetService/FoundationCompat.swift
index eebcade..59bcb78 100644
--- a/Sources/NetService/FoundationCompat.swift
+++ b/Sources/NetService/FoundationCompat.swift
@@ -1,5 +1,9 @@
 import CoreFoundation
 
+#if !os(Linux) || compiler(>=5.3)
+internal let kCFSocketReadCallBack = CFSocketCallBackType.readCallBack.rawValue
+#endif
+
 #if os(Linux) && !compiler(>=5.0)
 import class Foundation.RunLoop
 import struct Foundation.RunLoopMode
diff --git a/Sources/NetService/NetService.swift b/Sources/NetService/NetService.swift
index d501c20..a1e262f 100644
--- a/Sources/NetService/NetService.swift
+++ b/Sources/NetService/NetService.swift
@@ -356,7 +356,7 @@ public class NetService {
 
         var context = CFSocketContext(version: 0, info: info, retain: nil, release: nil, copyDescription: nil)
 
-        socket = CFSocketCreateWithNative(nil, fd, CFOptionFlags(CFSocketCallBackType.readCallBack.rawValue), _processResult, &context)
+        socket = CFSocketCreateWithNative(nil, fd, CFOptionFlags(kCFSocketReadCallBack), _processResult, &context)
 
         // Don't close the underlying socket on invalidate, as it is owned by dns_sd.
         var socketFlags = CFSocketGetSocketFlags(socket)
diff --git a/Sources/NetService/NetServiceBrowser.swift b/Sources/NetService/NetServiceBrowser.swift
index 23f365f..6ac9a0a 100644
--- a/Sources/NetService/NetServiceBrowser.swift
+++ b/Sources/NetService/NetServiceBrowser.swift
@@ -178,7 +178,7 @@ public class NetServiceBrowser {
         let info = Unmanaged.passUnretained(self).toOpaque()
 
         var context = CFSocketContext(version: 0, info: info, retain: nil, release: nil, copyDescription: nil)
-        socket = CFSocketCreateWithNative(nil, fd, CFOptionFlags(CFSocketCallBackType.readCallBack.rawValue), _processResult, &context)
+        socket = CFSocketCreateWithNative(nil, fd, CFOptionFlags(kCFSocketReadCallBack), _processResult, &context)
 
         // Don't close the underlying socket on invalidate, as it is owned by dns_sd.
         var socketFlags = CFSocketGetSocketFlags(socket)