diff --git a/CHANGES b/CHANGES
index db2ac6a730..87f5e01a48 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,7 @@
+5243.	[bug]		Fix a possible race between dispatcher and socket
+			code in a high-load cold-cache resolver scenario.
+			[GL #943]
+
 5242.	[bug]		In relaxed qname minimizatiom mode, fall back to
 			normal resolution when encountering a lame
 			delegation, and use _.domain/A queries rather
diff --git a/lib/isc/unix/socket.c b/lib/isc/unix/socket.c
index 2c97e6e697..fc93d369b5 100644
--- a/lib/isc/unix/socket.c
+++ b/lib/isc/unix/socket.c
@@ -2596,15 +2596,16 @@ isc_socket_open(isc_socket_t *sock0) {
 
 	REQUIRE(VALID_SOCKET(sock));
 
-	REQUIRE(isc_refcount_current(&sock->references) == 1);
-	/*
-	 * We don't need to retain the lock hereafter, since no one else has
-	 * this socket.
-	 */
+	LOCK(&sock->lock);
+
+	REQUIRE(isc_refcount_current(&sock->references) >= 1);
 	REQUIRE(sock->fd == -1);
 	REQUIRE(sock->threadid == -1);
 
 	result = opensocket(sock->manager, sock, NULL);
+
+	UNLOCK(&sock->lock);
+
 	if (result != ISC_R_SUCCESS) {
 		sock->fd = -1;
 	} else {