diff --git a/CHANGES b/CHANGES
index de454fddff..7850fae423 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,7 @@
+4219.	[bug]		Set event->result to ISC_R_WOULDBLOCK on EWOULDBLOCK,
+			EGAIN when these soft error are not retried for
+			isc_socket_send*().
+
 4217.	[protocol]	Add support for CSYNC. [RT #40532]
 
 4216.	[cleanup]	Silence static analysis warnings. [RT #40649]
diff --git a/lib/isc/include/isc/result.h b/lib/isc/include/isc/result.h
index ed1bc63e73..f6088d9e39 100644
--- a/lib/isc/include/isc/result.h
+++ b/lib/isc/include/isc/result.h
@@ -89,9 +89,10 @@
 #define ISC_R_BADBASE32			60	/*%< bad base32 encoding */
 #define ISC_R_UNSET			61	/*%< unset */
 #define ISC_R_MULTIPLE			62	/*%< multiple */
+#define ISC_R_WOULDBLOCK		63	/*%< would block */
 
 /*% Not a result code: the number of results. */
-#define ISC_R_NRESULTS 			63
+#define ISC_R_NRESULTS 			64
 
 ISC_LANG_BEGINDECLS
 
diff --git a/lib/isc/result.c b/lib/isc/result.c
index 6cbd8b4722..27927e8f25 100644
--- a/lib/isc/result.c
+++ b/lib/isc/result.c
@@ -104,6 +104,7 @@ static const char *description[ISC_R_NRESULTS] = {
 	"bad base32 encoding",			/*%< 60 */
 	"unset",				/*%< 61 */
 	"multiple",				/*%< 62 */
+	"would block",				/*%< 63 */
 };
 
 #define ISC_RESULT_RESULTSET			2
diff --git a/lib/isc/unix/socket.c b/lib/isc/unix/socket.c
index 20a246619a..833243c121 100644
--- a/lib/isc/unix/socket.c
+++ b/lib/isc/unix/socket.c
@@ -1876,8 +1876,11 @@ doio_send(isc__socket_t *sock, isc_socketevent_t *dev) {
 		if (send_errno == EINTR && ++attempts < NRETRIES)
 			goto resend;
 
-		if (SOFT_ERROR(send_errno))
+		if (SOFT_ERROR(send_errno)) {
+			if (errno == EWOULDBLOCK || errno == EAGAIN)
+				dev->result = ISC_R_WOULDBLOCK;
 			return (DOIO_SOFT);
+		}
 
 #define SOFT_OR_HARD(_system, _isc) \
 	if (send_errno == _system) { \