diff --git a/include/jemalloc/internal/cache_bin.h b/include/jemalloc/internal/cache_bin.h
index cb137af9..3ca7e287 100644
--- a/include/jemalloc/internal/cache_bin.h
+++ b/include/jemalloc/internal/cache_bin.h
@@ -616,7 +616,7 @@ struct cache_bin_fill_ctl_s {
  * This is to avoid stack overflow when we do batch edata look up, which
  * reserves a nflush * sizeof(emap_batch_lookup_result_t) stack variable.
  */
-#define CACHE_BIN_NFLUSH_BATCH_MAX (VARIABLE_ARRAY_SIZE_MAX >> LG_SIZEOF_PTR)
+#define CACHE_BIN_NFLUSH_BATCH_MAX ((VARIABLE_ARRAY_SIZE_MAX >> LG_SIZEOF_PTR) - 1)
 
 /*
  * Filling and flushing are done in batch, on arrays of void *s.  For filling,