diff --git a/CHANGELOG.md b/CHANGELOG.md
index 348e1dc86ba9c..357714b030b1a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -46,6 +46,7 @@
 * [11539](https://github.com/grafana/loki/pull/11539) **kaviraj,ashwanthgoli** Support caching /series and /labels query results
 * [11545](https://github.com/grafana/loki/pull/11545) **dannykopping** Force correct memcached timeout when fetching chunks.
 * [11589](https://github.com/grafana/loki/pull/11589) **ashwanthgoli** Results Cache: Adds `query_length_served` cache stat to measure the length of the query served from cache.
+* [11654](https://github.com/grafana/loki/pull/11654) **dannykopping** Cache: atomically check background cache size limit correctly. 
 
 ##### Fixes
 * [11074](https://github.com/grafana/loki/pull/11074) **hainenber** Fix panic in lambda-promtail due to mishandling of empty DROP_LABELS env var.
diff --git a/pkg/storage/chunk/cache/background.go b/pkg/storage/chunk/cache/background.go
index 16feb62551f5b..299444c6a54e0 100644
--- a/pkg/storage/chunk/cache/background.go
+++ b/pkg/storage/chunk/cache/background.go
@@ -148,8 +148,11 @@ func (c *backgroundCache) Store(ctx context.Context, keys []string, bufs [][]byt
 		}
 
 		size := bgWrite.size()
-		newSize := c.size.Load() + int64(size)
+		// prospectively add new size
+		newSize := c.size.Add(int64(size))
 		if newSize > int64(c.sizeLimit) {
+			// subtract it since we've exceeded the limit
+			c.size.Sub(int64(size))
 			c.failStore(ctx, size, num, "queue at byte size limit")
 			return nil
 		}