diff --git a/lib/isc/include/isc/result.h b/lib/isc/include/isc/result.h
index 2ddb075f8d..9677dad5a3 100644
--- a/lib/isc/include/isc/result.h
+++ b/lib/isc/include/isc/result.h
@@ -64,8 +64,9 @@
 #define ISC_R_NOTCONNECTED		40	/* socket is not connected */
 #define ISC_R_RANGE			41	/* out of range */
 #define ISC_R_NOENTROPY			42	/* out of entropy */
+#define ISC_R_MULTICAST			43	/* invalid use of multicast */
 
-#define ISC_R_NRESULTS 			43	/* Number of results */
+#define ISC_R_NRESULTS 			44	/* Number of results */
 
 ISC_LANG_BEGINDECLS
 
diff --git a/lib/isc/result.c b/lib/isc/result.c
index acea08dd8d..f09e4f241a 100644
--- a/lib/isc/result.c
+++ b/lib/isc/result.c
@@ -78,7 +78,8 @@ static const char *text[ISC_R_NRESULTS] = {
 	"file already exists",			/* 39 */
 	"socket is not connected",		/* 40 */
 	"out of range",				/* 41 */
-	"out of entropy"			/* 42 */
+	"out of entropy",			/* 42 */
+	"invalid use of multicast address"	/* 43 */
 };
 
 #define ISC_RESULT_RESULTSET			2