diff --git a/lib/isc/include/isc/result.h b/lib/isc/include/isc/result.h
index e655b3ebcd..941c04ebf7 100644
--- a/lib/isc/include/isc/result.h
+++ b/lib/isc/include/isc/result.h
@@ -20,7 +20,8 @@ typedef unsigned int isc_result_t;
 #define ISC_R_NORESOURCES		13	/* not enough resources */
 #define ISC_R_EOF			14	/* end of file */
 #define ISC_R_BOUND			15	/* already bound */
-#define ISC_R_LAST_ENTRY		15	/* last entry in the file */
+#define ISC_R_TASKSHUTDOWN		16	/* task was shut down */
+#define ISC_R_LAST_ENTRY		16	/* last entry in the list */
 
 #define ISC_R_UNEXPECTED		0xFFFFFFFFL
 
diff --git a/lib/isc/result.c b/lib/isc/result.c
index 85f7e382c1..2d0e69c77e 100644
--- a/lib/isc/result.c
+++ b/lib/isc/result.c
@@ -18,6 +18,7 @@ static char *text_table[ISC_R_LAST_ENTRY + 1] = {
 	"not enough free resources",		/* 13 */
 	"end of file",				/* 14 */
 	"socket already bound",			/* 15 */
+	"task was shut down",			/* 16 */
 };
 
 char *
diff --git a/lib/isc/task.c b/lib/isc/task.c
index 86f462e81f..15d8b5e207 100644
--- a/lib/isc/task.c
+++ b/lib/isc/task.c
@@ -303,7 +303,7 @@ isc_task_send(isc_task_t task, isc_event_t *eventp) {
 	if (discard) {
 		isc_event_free(&event);
 		*eventp = NULL;
-		return (ISC_R_NORESOURCES);
+		return (ISC_R_TASKSHUTDOWN);
 	}
 
 	if (was_idle) {