diff --git a/src/backend/libpq/pqcomm.c b/src/backend/libpq/pqcomm.c
index ea9543b366f..f2caf0efded 100644
--- a/src/backend/libpq/pqcomm.c
+++ b/src/backend/libpq/pqcomm.c
@@ -1615,7 +1615,7 @@ pq_setkeepaliveswin32(Port *port, int idle, int interval)
 int
 pq_getkeepalivesidle(Port *port)
 {
-#if defined(TCP_KEEPIDLE) || defined(TCP_KEEPALIVE) || defined(WIN32)
+#if defined(TCP_KEEPIDLE) || defined(TCP_KEEPALIVE_THRESHOLD) || defined(TCP_KEEPALIVE) || defined(WIN32)
 	if (port == NULL || IS_AF_UNIX(port->laddr.addr.ss_family))
 		return 0;
 
@@ -1627,7 +1627,8 @@ pq_getkeepalivesidle(Port *port)
 #ifndef WIN32
 		ACCEPT_TYPE_ARG3 size = sizeof(port->default_keepalives_idle);
 
-#ifdef TCP_KEEPIDLE
+#if defined(TCP_KEEPIDLE)
+		/* TCP_KEEPIDLE is the name of this option on Linux and *BSD */
 		if (getsockopt(port->sock, IPPROTO_TCP, TCP_KEEPIDLE,
 					   (char *) &port->default_keepalives_idle,
 					   &size) < 0)
@@ -1635,7 +1636,17 @@ pq_getkeepalivesidle(Port *port)
 			elog(LOG, "getsockopt(TCP_KEEPIDLE) failed: %m");
 			port->default_keepalives_idle = -1; /* don't know */
 		}
-#else
+#elif defined(TCP_KEEPALIVE_THRESHOLD)
+		/* TCP_KEEPALIVE_THRESHOLD is the name of this option on Solaris */
+		if (getsockopt(port->sock, IPPROTO_TCP, TCP_KEEPALIVE_THRESHOLD,
+					   (char *) &port->default_keepalives_idle,
+					   &size) < 0)
+		{
+			elog(LOG, "getsockopt(TCP_KEEPALIVE_THRESHOLD) failed: %m");
+			port->default_keepalives_idle = -1; /* don't know */
+		}
+#else							/* must have TCP_KEEPALIVE */
+		/* TCP_KEEPALIVE is the name of this option on macOS */
 		if (getsockopt(port->sock, IPPROTO_TCP, TCP_KEEPALIVE,
 					   (char *) &port->default_keepalives_idle,
 					   &size) < 0)
@@ -1643,7 +1654,7 @@ pq_getkeepalivesidle(Port *port)
 			elog(LOG, "getsockopt(TCP_KEEPALIVE) failed: %m");
 			port->default_keepalives_idle = -1; /* don't know */
 		}
-#endif   /* TCP_KEEPIDLE */
+#endif   /* KEEPIDLE/KEEPALIVE_THRESHOLD/KEEPALIVE */
 #else							/* WIN32 */
 		/* We can't get the defaults on Windows, so return "don't know" */
 		port->default_keepalives_idle = -1;
@@ -1662,7 +1673,8 @@ pq_setkeepalivesidle(int idle, Port *port)
 	if (port == NULL || IS_AF_UNIX(port->laddr.addr.ss_family))
 		return STATUS_OK;
 
-#if defined(TCP_KEEPIDLE) || defined(TCP_KEEPALIVE) || defined(SIO_KEEPALIVE_VALS)
+/* check SIO_KEEPALIVE_VALS here, not just WIN32, as some toolchains lack it */
+#if defined(TCP_KEEPIDLE) || defined(TCP_KEEPALIVE_THRESHOLD) || defined(TCP_KEEPALIVE) || defined(SIO_KEEPALIVE_VALS)
 	if (idle == port->keepalives_idle)
 		return STATUS_OK;
 
@@ -1681,14 +1693,24 @@ pq_setkeepalivesidle(int idle, Port *port)
 	if (idle == 0)
 		idle = port->default_keepalives_idle;
 
-#ifdef TCP_KEEPIDLE
+#if defined(TCP_KEEPIDLE)
+	/* TCP_KEEPIDLE is the name of this option on Linux and *BSD */
 	if (setsockopt(port->sock, IPPROTO_TCP, TCP_KEEPIDLE,
 				   (char *) &idle, sizeof(idle)) < 0)
 	{
 		elog(LOG, "setsockopt(TCP_KEEPIDLE) failed: %m");
 		return STATUS_ERROR;
 	}
-#else
+#elif defined(TCP_KEEPALIVE_THRESHOLD)
+	/* TCP_KEEPALIVE_THRESHOLD is the name of this option on Solaris */
+	if (setsockopt(port->sock, IPPROTO_TCP, TCP_KEEPALIVE_THRESHOLD,
+				   (char *) &idle, sizeof(idle)) < 0)
+	{
+		elog(LOG, "setsockopt(TCP_KEEPALIVE_THRESHOLD) failed: %m");
+		return STATUS_ERROR;
+	}
+#else							/* must have TCP_KEEPALIVE */
+	/* TCP_KEEPALIVE is the name of this option on macOS */
 	if (setsockopt(port->sock, IPPROTO_TCP, TCP_KEEPALIVE,
 				   (char *) &idle, sizeof(idle)) < 0)
 	{
@@ -1701,7 +1723,7 @@ pq_setkeepalivesidle(int idle, Port *port)
 #else							/* WIN32 */
 	return pq_setkeepaliveswin32(port, idle, port->keepalives_interval);
 #endif
-#else							/* TCP_KEEPIDLE || SIO_KEEPALIVE_VALS */
+#else							/* no way to set it */
 	if (idle != 0)
 	{
 		elog(LOG, "setting the keepalive idle time is not supported");
@@ -1751,7 +1773,7 @@ pq_setkeepalivesinterval(int interval, Port *port)
 	if (port == NULL || IS_AF_UNIX(port->laddr.addr.ss_family))
 		return STATUS_OK;
 
-#if defined(TCP_KEEPINTVL) || defined (SIO_KEEPALIVE_VALS)
+#if defined(TCP_KEEPINTVL) || defined(SIO_KEEPALIVE_VALS)
 	if (interval == port->keepalives_interval)
 		return STATUS_OK;
 
diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index 8b71ae7b779..e350a242e20 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -1280,7 +1280,8 @@ setKeepalivesIdle(PGconn *conn)
 	if (idle < 0)
 		idle = 0;
 
-#ifdef TCP_KEEPIDLE
+#if defined(TCP_KEEPIDLE)
+	/* TCP_KEEPIDLE is the name of this option on Linux and *BSD */
 	if (setsockopt(conn->sock, IPPROTO_TCP, TCP_KEEPIDLE,
 				   (char *) &idle, sizeof(idle)) < 0)
 	{
@@ -1291,9 +1292,20 @@ setKeepalivesIdle(PGconn *conn)
 						  SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
 		return 0;
 	}
-#else
-#ifdef TCP_KEEPALIVE
-	/* Darwin uses TCP_KEEPALIVE rather than TCP_KEEPIDLE */
+#elif defined(TCP_KEEPALIVE_THRESHOLD)
+	/* TCP_KEEPALIVE_THRESHOLD is the name of this option on Solaris */
+	if (setsockopt(conn->sock, IPPROTO_TCP, TCP_KEEPALIVE_THRESHOLD,
+				   (char *) &idle, sizeof(idle)) < 0)
+	{
+		char		sebuf[256];
+
+		appendPQExpBuffer(&conn->errorMessage,
+						  libpq_gettext("setsockopt(TCP_KEEPALIVE_THRESHOLD) failed: %s\n"),
+						  SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
+		return 0;
+	}
+#elif defined(TCP_KEEPALIVE)
+	/* TCP_KEEPALIVE is the name of this option on macOS */
 	if (setsockopt(conn->sock, IPPROTO_TCP, TCP_KEEPALIVE,
 				   (char *) &idle, sizeof(idle)) < 0)
 	{
@@ -1304,7 +1316,6 @@ setKeepalivesIdle(PGconn *conn)
 						  SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
 		return 0;
 	}
-#endif
 #endif
 
 	return 1;
@@ -1372,7 +1383,7 @@ setKeepalivesCount(PGconn *conn)
 
 	return 1;
 }
-#else							/* Win32 */
+#else							/* WIN32 */
 #ifdef SIO_KEEPALIVE_VALS
 /*
  * Enable keepalives and set the keepalive values on Win32,