diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0cc86a6f24f..f506cacb7f4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,7 @@ The stress tool `influx_stress` will be removed in a subsequent release. We reco
 
 ### Bugfixes
 
+- [#7786](https://github.com/influxdata/influxdb/pull/7786): Fix potential race condition in correctness of tsm1_cache memBytes statistic.
 - [#7784](https://github.com/influxdata/influxdb/pull/7784): Fix broken error return on meta client's UpdateUser and DropContinuousQuery methods.
 - [#7741](https://github.com/influxdata/influxdb/pull/7741): Fix string quoting and significantly improve performance of `influx_inspect export`.
 - [#7698](https://github.com/influxdata/influxdb/pull/7698): CLI was caching db/rp for insert into statements.
diff --git a/tsdb/engine/tsm1/cache.go b/tsdb/engine/tsm1/cache.go
index 297bb8d4767..f4c5244a9e9 100644
--- a/tsdb/engine/tsm1/cache.go
+++ b/tsdb/engine/tsm1/cache.go
@@ -423,8 +423,8 @@ func (c *Cache) increaseSize(delta uint64) {
 
 // decreaseSize decreases size by delta.
 func (c *Cache) decreaseSize(delta uint64) {
-	size := atomic.LoadUint64(&c.size)
-	atomic.StoreUint64(&c.size, size-delta)
+	// Per sync/atomic docs, bit-flip delta minus one to perform subtraction within AddUint64.
+	atomic.AddUint64(&c.size, ^(delta - 1))
 }
 
 // MaxSize returns the maximum number of bytes the cache may consume.