diff --git a/src/arena.c b/src/arena.c
index 4a383670..9a8e5d64 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -1023,6 +1023,7 @@ arena_cache_bin_fill_small(tsdn_t *tsdn, arena_t *arena,
     cache_bin_t *cache_bin, cache_bin_info_t *cache_bin_info, szind_t binind,
     const unsigned nfill) {
 	assert(cache_bin_ncached_get_local(cache_bin, cache_bin_info) == 0);
+	assert(nfill != 0);
 
 	const bin_info_t *bin_info = &bin_infos[binind];
 
diff --git a/src/tcache.c b/src/tcache.c
index 02627896..d57574ca 100644
--- a/src/tcache.c
+++ b/src/tcache.c
@@ -257,6 +257,9 @@ tcache_alloc_small_hard(tsdn_t *tsdn, arena_t *arena,
 	assert(!tcache_bin_disabled(binind, cache_bin, tcache_slow));
 	unsigned nfill = cache_bin_info_ncached_max_get(cache_bin,
 	    &cache_bin->bin_info) >> tcache_slow->lg_fill_div[binind];
+	if (nfill == 0) {
+		nfill = 1;
+	}
 	arena_cache_bin_fill_small(tsdn, arena, cache_bin,
 	    &cache_bin->bin_info, binind, nfill);
 	tcache_slow->bin_refilled[binind] = true;