diff --git a/files/set.go b/files/set.go
index bcb7048df..0f0d657f2 100644
--- a/files/set.go
+++ b/files/set.go
@@ -49,6 +49,7 @@ func (m *Set) Replace(id uint, fs []scanner.File) {
 	}
 
 	m.Lock()
+	log("Replace", id, len(fs))
 	if len(fs) == 0 || !m.equals(id, fs) {
 		m.changes[id]++
 		m.replace(id, fs)
@@ -65,6 +66,7 @@ func (m *Set) ReplaceWithDelete(id uint, fs []scanner.File) {
 	}
 
 	m.Lock()
+	log("ReplaceWithDelete", id, len(fs))
 	if len(fs) == 0 || !m.equals(id, fs) {
 		m.changes[id]++
 
@@ -102,7 +104,9 @@ func (m *Set) Update(id uint, fs []scanner.File) {
 	if debug {
 		l.Debugf("Update(%d, [%d])", id, len(fs))
 	}
+
 	m.Lock()
+	log("Update", id, len(fs))
 	m.update(id, fs)
 	m.changes[id]++
 	m.Unlock()
@@ -220,6 +224,7 @@ func (m *Set) equals(id uint, fs []scanner.File) bool {
 func (m *Set) update(cid uint, fs []scanner.File) {
 	remFiles := m.remoteKey[cid]
 	if remFiles == nil {
+		printLog()
 		l.Fatalln("update before replace for cid", cid)
 	}
 	for _, f := range fs {
diff --git a/files/set_debug.go b/files/set_debug.go
new file mode 100644
index 000000000..76dac1e28
--- /dev/null
+++ b/files/set_debug.go
@@ -0,0 +1,51 @@
+package files
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/calmh/syncthing/cid"
+)
+
+type logEntry struct {
+	time   time.Time
+	method string
+	cid    uint
+	node   string
+	nfiles int
+}
+
+func (l logEntry) String() string {
+	return fmt.Sprintf("%v: %s cid:%d node:%s nfiles:%d", l.time, l.method, l.cid, l.node, l.nfiles)
+}
+
+var (
+	debugLog  [10]logEntry
+	debugNext int
+	cm        *cid.Map
+)
+
+func SetCM(m *cid.Map) {
+	cm = m
+}
+
+func log(method string, id uint, nfiles int) {
+	e := logEntry{
+		time:   time.Now(),
+		method: method,
+		cid:    id,
+		nfiles: nfiles,
+	}
+	if cm != nil {
+		e.node = cm.Name(id)
+	}
+	debugLog[debugNext] = e
+	debugNext = (debugNext + 1) % len(debugLog)
+}
+
+func printLog() {
+	l.Debugln("--- Consistency error ---")
+	for _, e := range debugLog {
+		l.Debugln(e)
+	}
+}
diff --git a/model/model.go b/model/model.go
index a05de8afd..01519f267 100644
--- a/model/model.go
+++ b/model/model.go
@@ -98,6 +98,9 @@ func NewModel(indexDir string, cfg *config.Configuration, clientName, clientVers
 		sup:           suppressor{threshold: int64(cfg.Options.MaxChangeKbps)},
 	}
 
+	// TEMP: #344
+	files.SetCM(m.cm)
+
 	var timeout = 20 * 60 // seconds
 	if t := os.Getenv("STDEADLOCKTIMEOUT"); len(t) > 0 {
 		it, err := strconv.Atoi(t)