diff --git a/tsdb/engine/tsm1/compact.go b/tsdb/engine/tsm1/compact.go
index 2e2dfe25cfd..9ab37139ee6 100644
--- a/tsdb/engine/tsm1/compact.go
+++ b/tsdb/engine/tsm1/compact.go
@@ -37,13 +37,24 @@ const (
 )
 
 var (
-	errMaxFileExceeded      = fmt.Errorf("max file exceeded")
-	errSnapshotsDisabled    = fmt.Errorf("snapshots disabled")
-	errCompactionsDisabled  = fmt.Errorf("compactions disabled")
-	errCompactionAborted    = fmt.Errorf("compaction aborted")
-	errCompactionInProgress = fmt.Errorf("compaction in progress")
+	errMaxFileExceeded     = fmt.Errorf("max file exceeded")
+	errSnapshotsDisabled   = fmt.Errorf("snapshots disabled")
+	errCompactionsDisabled = fmt.Errorf("compactions disabled")
+	errCompactionAborted   = fmt.Errorf("compaction aborted")
 )
 
+type errCompactionInProgress struct {
+	err error
+}
+
+// Error returns the string representation of the error, to satisfy the error interface.
+func (e errCompactionInProgress) Error() string {
+	if e.err != nil {
+		return fmt.Sprintf("compaction in progress: %s", e.err)
+	}
+	return "compaction in progress"
+}
+
 // CompactionGroup represents a list of files eligible to be compacted together.
 type CompactionGroup []string
 
@@ -492,10 +503,11 @@ func (c *DefaultPlanner) Plan(lastWrite time.Time) []CompactionGroup {
 // findGenerations groups all the TSM files by generation based
 // on their filename, then returns the generations in descending order (newest first).
 func (c *DefaultPlanner) findGenerations() tsmGenerations {
-	c.mu.RLock()
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
 	last := c.lastFindGenerations
 	lastGen := c.lastGenerations
-	c.mu.RUnlock()
 
 	if !last.IsZero() && c.FileStore.LastModified().Equal(last) {
 		return lastGen
@@ -525,10 +537,8 @@ func (c *DefaultPlanner) findGenerations() tsmGenerations {
 		sort.Sort(orderedGenerations)
 	}
 
-	c.mu.Lock()
 	c.lastFindGenerations = genTime
 	c.lastGenerations = orderedGenerations
-	c.mu.Unlock()
 
 	return orderedGenerations
 }
@@ -726,7 +736,7 @@ func (c *Compactor) CompactFull(tsmFiles []string) ([]string, error) {
 	}
 
 	if !c.add(tsmFiles) {
-		return nil, errCompactionInProgress
+		return nil, errCompactionInProgress{}
 	}
 	defer c.remove(tsmFiles)
 
@@ -755,7 +765,7 @@ func (c *Compactor) CompactFast(tsmFiles []string) ([]string, error) {
 	}
 
 	if !c.add(tsmFiles) {
-		return nil, errCompactionInProgress
+		return nil, errCompactionInProgress{}
 	}
 	defer c.remove(tsmFiles)
 
@@ -800,7 +810,7 @@ func (c *Compactor) writeNewFiles(generation, sequence int, iter KeyIterator) ([
 				return nil, err
 			}
 			break
-		} else if err == errCompactionInProgress {
+		} else if _, ok := err.(errCompactionInProgress); ok {
 			// Don't clean up the file as another compaction is using it.  This should not happen as the
 			// planner keeps track of which files are assigned to compaction plans now.
 			return nil, err
@@ -822,7 +832,7 @@ func (c *Compactor) writeNewFiles(generation, sequence int, iter KeyIterator) ([
 func (c *Compactor) write(path string, iter KeyIterator) (err error) {
 	fd, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR|os.O_EXCL, 0666)
 	if err != nil {
-		return errCompactionInProgress
+		return errCompactionInProgress{err: err}
 	}
 
 	// Create the write for the new TSM file.
diff --git a/tsdb/engine/tsm1/engine.go b/tsdb/engine/tsm1/engine.go
index c2e894ac58d..3c152ec089c 100644
--- a/tsdb/engine/tsm1/engine.go
+++ b/tsdb/engine/tsm1/engine.go
@@ -1181,10 +1181,9 @@ func (e *Engine) compactTSMLevel(fast bool, level int, quit <-chan struct{}) {
 		case <-t.C:
 			s := e.levelCompactionStrategy(fast, level)
 			if s != nil {
-				// Release the files in the compaction plan
-				defer e.CompactionPlan.Release(s.compactionGroups)
-
 				s.Apply()
+				// Release the files in the compaction plan
+				e.CompactionPlan.Release(s.compactionGroups)
 			}
 
 		}
@@ -1203,9 +1202,9 @@ func (e *Engine) compactTSMFull(quit <-chan struct{}) {
 		case <-t.C:
 			s := e.fullCompactionStrategy()
 			if s != nil {
-				// Release the files in the compaction plan
-				defer e.CompactionPlan.Release(s.compactionGroups)
 				s.Apply()
+				// Release the files in the compaction plan
+				e.CompactionPlan.Release(s.compactionGroups)
 			}
 
 		}
@@ -1291,10 +1290,11 @@ func (s *compactionStrategy) compactGroup(groupNum int) {
 	}()
 
 	if err != nil {
-		if err == errCompactionsDisabled || err == errCompactionInProgress {
+		_, inProgress := err.(errCompactionInProgress)
+		if err == errCompactionsDisabled || inProgress {
 			s.logger.Info(fmt.Sprintf("aborted %s compaction group (%d). %v", s.description, groupNum, err))
 
-			if err == errCompactionInProgress {
+			if _, ok := err.(errCompactionInProgress); ok {
 				time.Sleep(time.Second)
 			}
 			return