diff --git a/.env.example b/.env.example
index e250b04..d683b82 100644
--- a/.env.example
+++ b/.env.example
@@ -2,6 +2,9 @@
 APP_SECRET=CHANGE_ME_TO_A_LONG_RANDOM_SECRET
 LISTEN_ADDR=0.0.0.0:8080
 HTTPS_ONLY=true
+# Verbose per-cycle stats-collector logging (raw TS3 reading vs what got
+# written to the RRD). Noisy, meant for troubleshooting only.
+DEBUG=false
 
 # Origins allowed to embed /embed/channel in an iframe. Space-separated, origins only.
 FRAME_ANCESTORS=https://www.example.org
diff --git a/VERSION b/VERSION
index 1c09c74..449d7e7 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.3.3
+0.3.6
diff --git a/cmd/ts3monolith/main.go b/cmd/ts3monolith/main.go
index 36f258a..9febcb0 100644
--- a/cmd/ts3monolith/main.go
+++ b/cmd/ts3monolith/main.go
@@ -66,14 +66,24 @@ func collect(ctx context.Context, cfg config.Config, tq *ts3.Query, rm *rrd.Mana
 		// more than it reads as useful information -- so, deliberately,
 		// a true "server went empty for a while" no longer shows as 0 in
 		// the graph, same trade-off the original app made.
+		raw := n
 		if n == 0 {
 			c2, cancel2 := context.WithTimeout(ctx, 2*time.Second)
 			last, lastErr := rm.Last(c2)
 			cancel2()
-			if lastErr == nil {
+			if lastErr != nil {
+				log.Printf("collect: raw=0, rrd lastupdate failed (writing raw 0): %v", lastErr)
+			} else {
 				n = last
 			}
 		}
+		// DEBUG=1 turns on a log line for every single collection cycle
+		// (raw TS3 reading vs. what actually got written to the RRD) --
+		// useful while diagnosing the stats collector, far too noisy to
+		// leave on permanently (one line per STATS_INTERVAL, forever).
+		if cfg.Debug {
+			log.Printf("collect: raw=%d written=%d", raw, n)
+		}
 		c3, cancel3 := context.WithTimeout(ctx, 5*time.Second)
 		defer cancel3()
 		if err := rm.Update(c3, n); err != nil {
diff --git a/internal/config/config.go b/internal/config/config.go
index 11cb201..71d490e 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -15,6 +15,7 @@ type Config struct {
 	ListenAddr        string
 	AppSecret         string
 	HTTPSOnly         bool
+	Debug             bool
 	FrameAncestors    []string
 	TrustedProxies    []*net.IPNet
 	TSQueryHost       string
@@ -39,6 +40,7 @@ func Load() (Config, error) {
 		return c, errors.New("APP_SECRET must contain at least 32 characters")
 	}
 	c.HTTPSOnly = envBool("HTTPS_ONLY", true)
+	c.Debug = envBool("DEBUG", false)
 
 	var err error
 	c.FrameAncestors, err = frameAncestors(os.Getenv("FRAME_ANCESTORS"))
diff --git a/packaging/ts3monolith.default b/packaging/ts3monolith.default
index 5a1438e..af4fd88 100644
--- a/packaging/ts3monolith.default
+++ b/packaging/ts3monolith.default
@@ -27,3 +27,7 @@ RRDTOOL=rrdtool
 RRD_PATH=/var/lib/ts3monolith/online.rrd
 GRAPH_DIR=/var/lib/ts3monolith/graphs
 STATS_INTERVAL=60s
+# Szczegolowy log kazdego cyklu zbierania statystyk (surowy odczyt z TS3 vs
+# co faktycznie trafilo do RRD). Przydatne tylko przy diagnozowaniu -- zalewa
+# journald jednym wpisem na STATS_INTERVAL, zostaw wylaczone na co dzien.
+DEBUG=false