diff --git a/nsprpub/pr/src/io/prsocket.c b/nsprpub/pr/src/io/prsocket.c
index 8cd4f0438371..0a18d4b2e8e6 100644
--- a/nsprpub/pr/src/io/prsocket.c
+++ b/nsprpub/pr/src/io/prsocket.c
@@ -315,9 +315,9 @@ static PRStatus PR_CALLBACK SocketConnectContinue(
     if (fd->secret->alreadyConnected) {
         fd->secret->alreadyConnected = PR_FALSE;
     }
-    // TCP Fast Open on Windows must use ConnectEx, which uses overlapped
-    // input/output.
-    // To get result we need to use GetOverlappedResult.
+    /* TCP Fast Open on Windows must use ConnectEx, which uses overlapped
+     * input/output.
+     * To get result we need to use GetOverlappedResult. */
     if (fd->secret->overlappedActive) {
         PR_ASSERT(fd->secret->nonblocking);
         PRInt32 rvSent;
@@ -325,9 +325,9 @@ static PRStatus PR_CALLBACK SocketConnectContinue(
             fd->secret->overlappedActive = FALSE;
             PR_LOG(_pr_io_lm, PR_LOG_MIN,
                ("SocketConnectContinue GetOverlappedResult succeeded\n"));
-            // When ConnectEx is used, all previously set socket options and
-            // property are not enabled and to enable them
-            // SO_UPDATE_CONNECT_CONTEXT option need to be set.
+            /* When ConnectEx is used, all previously set socket options and
+             * property are not enabled and to enable them
+             * SO_UPDATE_CONNECT_CONTEXT option need to be set. */
             if (setsockopt((SOCKET)osfd, SOL_SOCKET, SO_UPDATE_CONNECT_CONTEXT, NULL, 0) != 0) {
                 err = WSAGetLastError();
                 PR_LOG(_pr_io_lm, PR_LOG_MIN,
@@ -1198,7 +1198,7 @@ static PRIOMethods tcpMethods = {
 	SocketSend,
 	(PRRecvfromFN)_PR_InvalidInt,
 #if defined(_WIN64) && defined(WIN95)
-	SocketTCPSendTo, // This is for fast open. We imitate Linux interface.
+	SocketTCPSendTo, /* This is for fast open. We imitate Linux interface. */
 #else
 	(PRSendtoFN)_PR_InvalidInt,
 #endif
diff --git a/nsprpub/pr/src/md/windows/w95sock.c b/nsprpub/pr/src/md/windows/w95sock.c
index 89d547fb2a96..f0712c157fe1 100644
--- a/nsprpub/pr/src/md/windows/w95sock.c
+++ b/nsprpub/pr/src/md/windows/w95sock.c
@@ -410,7 +410,7 @@ _PR_MD_TCPSENDTO(PRFileDesc *fd, const void *buf, PRInt32 amount, PRIntn flags,
         return -1;
     }
 
-    // ConnectEx requires the socket to be initially bound. We will use INADDR_ANY
+    /* ConnectEx requires the socket to be initially bound. We will use INADDR_ANY. */
     PRNetAddr bindAddr;
     memset(&bindAddr, 0, sizeof(bindAddr));
     if (addr->raw.family == PR_AF_INET) {
@@ -432,13 +432,13 @@ _PR_MD_TCPSENDTO(PRFileDesc *fd, const void *buf, PRInt32 amount, PRIntn flags,
 
     rvSent = 0;
     memset(&fd->secret->ol, 0, sizeof(fd->secret->ol));
-    // ConnectEx return TRUE on a success and FALSE on an error.
+    /* ConnectEx return TRUE on a success and FALSE on an error. */
     if (_pr_win_connectex( (SOCKET)osfd, (struct sockaddr *) addr,
                            addrlen, buf, amount,
                            &rvSent, &fd->secret->ol) == TRUE) {
-        // When ConnectEx is used, all previously set socket options and
-        // property are not enabled and to enable them
-        // SO_UPDATE_CONNECT_CONTEXT option need to be set.
+        /* When ConnectEx is used, all previously set socket options and
+         * property are not enabled and to enable them
+         * SO_UPDATE_CONNECT_CONTEXT option need to be set. */
         rv = setsockopt((SOCKET)osfd, SOL_SOCKET, SO_UPDATE_CONNECT_CONTEXT, NULL, 0);
         if (rv != 0) {
             err = WSAGetLastError();
@@ -447,10 +447,10 @@ _PR_MD_TCPSENDTO(PRFileDesc *fd, const void *buf, PRInt32 amount, PRIntn flags,
             _PR_MD_MAP_SETSOCKOPT_ERROR(err);
             return -1;
         }
-        // We imitate Linux here. SendTo will return number of bytes send but
-        // it can not return connection success at the same time, so we return
-        // number of bytes send and "connection success" will be return on the
-        // connectcontinue.
+        /* We imitate Linux here. SendTo will return number of bytes send but
+         * it can not return connection success at the same time, so we return
+         * number of bytes send and "connection success" will be return on the
+         * connectcontinue. */
         fd->secret->alreadyConnected = PR_TRUE;
         return rvSent;
     } else {
@@ -461,13 +461,13 @@ _PR_MD_TCPSENDTO(PRFileDesc *fd, const void *buf, PRInt32 amount, PRIntn flags,
             _PR_MD_MAP_CONNECT_ERROR(err);
             return -1;
         } else if (fd->secret->nonblocking) {
-            // Remember that overlapped structure is set. We will neede to get
-            // the final result of ConnectEx call.
+            /* Remember that overlapped structure is set. We will neede to get
+             * the final result of ConnectEx call. */
             fd->secret->overlappedActive = PR_TRUE;
             _PR_MD_MAP_CONNECT_ERROR(WSAEWOULDBLOCK);
-            // ConnectEx will copy supplied data to a internal buffer and send
-            // them during Fast Open or after connect. Therefore we can assumed
-            // this data already send.
+            /* ConnectEx will copy supplied data to a internal buffer and send
+             * them during Fast Open or after connect. Therefore we can assumed
+             * this data already send. */
             return amount;
         }
         while (err == ERROR_IO_PENDING) {
diff --git a/nsprpub/pr/src/pthreads/ptio.c b/nsprpub/pr/src/pthreads/ptio.c
index 655d15b4b52f..53206bd165e3 100644
--- a/nsprpub/pr/src/pthreads/ptio.c
+++ b/nsprpub/pr/src/pthreads/ptio.c
@@ -2056,14 +2056,15 @@ static PRInt32 pt_SendTo(
     return bytes;
 }  /* pt_SendTo */
 
-// Linux uses SendTo to send data during TCP Fast Open. OSX uses connectx, but
-// we will make it imitate the Linux's interface.
+#if defined(LINUX) || defined(DARWIN)
+/* Linux uses SendTo to send data during TCP Fast Open. OSX uses connectx, but
+ * we will make it imitate the Linux's interface. */
 static PRInt32 pt_TCP_SendTo(
     PRFileDesc *fd, const void *buf,
     PRInt32 amount, PRIntn flags, const PRNetAddr *addr,
     PRIntervalTime timeout)
 {
-#if !defined(DARWIN) || HAS_CONNECTX
+#if defined(LINUX) || HAS_CONNECTX
     PRInt32 syserrno, bytes = -1;
     PRBool fNeedContinue = PR_FALSE;
     pt_SockLen addr_len;
@@ -2084,8 +2085,8 @@ static PRInt32 pt_TCP_SendTo(
 #ifdef _PR_HAVE_SOCKADDR_LEN
         md_af = AF_INET6;
 #else
-        // If _PR_INET6 is defined and it is PR_AF_INET6 we set family
-        // to AF_INET6.
+        /* If _PR_INET6 is defined and it is PR_AF_INET6 we set family
+         * to AF_INET6. */
         addrCopy = *addr;
         addrCopy.raw.family = AF_INET6;
         addrp = &addrCopy;
@@ -2094,8 +2095,8 @@ static PRInt32 pt_TCP_SendTo(
 #endif
 
 #ifdef _PR_HAVE_SOCKADDR_LEN
-    // if _PR_HAVE_SOCKADDR_LEN is defined and it is PR_AF_INET6 we set family
-    // to AF_INET6 and we set address length.
+    /* if _PR_HAVE_SOCKADDR_LEN is defined and it is PR_AF_INET6 we set family
+     * to AF_INET6 and we set address length. */
     addrCopy = *addr;
     ((struct sockaddr*)&addrCopy)->sa_len = addr_len;
     ((struct sockaddr*)&addrCopy)->sa_family = md_af;
@@ -2143,11 +2144,12 @@ static PRInt32 pt_TCP_SendTo(
         pt_MapError(_PR_MD_MAP_SENDTO_ERROR, syserrno);
     }
     return bytes;
-#else
+#else /* !HAS_CONNECTX */
     PR_SetError(PR_NOT_IMPLEMENTED_ERROR, 0);
     return -1;
 #endif
 }  /* pt_TCP_SendTo */
+#endif /* LINUX || DARWIN */
 
 static PRInt32 pt_RecvFrom(PRFileDesc *fd, void *buf, PRInt32 amount,
     PRIntn flags, PRNetAddr *addr, PRIntervalTime timeout)
@@ -3260,7 +3262,11 @@ static PRIOMethods _pr_tcp_methods = {
     pt_Recv,
     pt_Send,
     (PRRecvfromFN)_PR_InvalidInt,
-    pt_TCP_SendTo, // This is for TCP Fast Open. Linux uses SendTo function for this. OSX uses connectx, but we imitate Linux.
+#if defined(LINUX) || defined(DARWIN)
+    pt_TCP_SendTo, /* This is for TCP Fast Open. Linux uses SendTo function for this. OSX uses connectx, but we imitate Linux. */
+#else
+    (PRSendtoFN)_PR_InvalidInt,
+#endif
     pt_Poll,
     pt_AcceptRead,
     pt_TransmitFile,