diff --git a/usr.bin/sed/main.c b/usr.bin/sed/main.c
index d54a7c11d1a7..e48c85ea9ae4 100644
--- a/usr.bin/sed/main.c
+++ b/usr.bin/sed/main.c
@@ -250,6 +250,8 @@ cu_fgets(char *buf, int n, int *more)
 			s = script->s;
 			state = ST_STRING;
 			goto again;
+		default:
+			__unreachable();
 		}
 	case ST_FILE:
 		if ((p = fgets(buf, n, f)) != NULL) {