diff --git a/src/mem/cache/tags/fa_lru.cc b/src/mem/cache/tags/fa_lru.cc
index 5c2d05b383..01f0aa256e 100644
--- a/src/mem/cache/tags/fa_lru.cc
+++ b/src/mem/cache/tags/fa_lru.cc
@@ -124,7 +124,8 @@ void
 FALRU::invalidate(CacheBlk *blk)
 {
     // Erase block entry reference in the hash table
-    auto num_erased = tagHash.erase(std::make_pair(blk->tag, blk->isSecure()));
+    auto num_erased M5_VAR_USED =
+        tagHash.erase(std::make_pair(blk->tag, blk->isSecure()));
 
     // Sanity check; only one block reference should be erased
     assert(num_erased == 1);