diff --git a/src/syscall/syscall_linux.go b/src/syscall/syscall_linux.go
index 76afab0bfc..2d2863690d 100644
--- a/src/syscall/syscall_linux.go
+++ b/src/syscall/syscall_linux.go
@@ -541,15 +541,17 @@ func Recvmsg(fd int, p, oob []byte, flags int) (n, oobn int, recvflags int, from
 	}
 	var dummy byte
 	if len(oob) > 0 {
-		var sockType int
-		sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
-		if err != nil {
-			return
-		}
-		// receive at least one normal byte
-		if sockType != SOCK_DGRAM && len(p) == 0 {
-			iov.Base = &dummy
-			iov.SetLen(1)
+		if len(p) == 0 {
+			var sockType int
+			sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
+			if err != nil {
+				return
+			}
+			// receive at least one normal byte
+			if sockType != SOCK_DGRAM {
+				iov.Base = &dummy
+				iov.SetLen(1)
+			}
 		}
 		msg.Control = &oob[0]
 		msg.SetControllen(len(oob))
@@ -593,15 +595,17 @@ func SendmsgN(fd int, p, oob []byte, to Sockaddr, flags int) (n int, err error)
 	}
 	var dummy byte
 	if len(oob) > 0 {
-		var sockType int
-		sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
-		if err != nil {
-			return 0, err
-		}
-		// send at least one normal byte
-		if sockType != SOCK_DGRAM && len(p) == 0 {
-			iov.Base = &dummy
-			iov.SetLen(1)
+		if len(p) == 0 {
+			var sockType int
+			sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
+			if err != nil {
+				return 0, err
+			}
+			// send at least one normal byte
+			if sockType != SOCK_DGRAM {
+				iov.Base = &dummy
+				iov.SetLen(1)
+			}
 		}
 		msg.Control = &oob[0]
 		msg.SetControllen(len(oob))