diff --git a/src/shknam.c b/src/shknam.c
index 45c9aca39..32e3677f0 100644
--- a/src/shknam.c
+++ b/src/shknam.c
@@ -536,6 +536,7 @@ nameshk(struct monst* shk, const char* const* nlp)
             for (mtmp = fmon; mtmp; mtmp = mtmp->nmon) {
                 if (DEADMONSTER(mtmp) || (mtmp == shk) || !mtmp->isshk)
                     continue;
+                assert(has_eshk(mtmp));
                 if (strcmp(ESHK(mtmp)->shknam, shname))
                     continue;
                 name_wanted = names_avail; /* try a random name */