diff --git a/src/039-nonblocking-channel-operations/nonblocking-channel-operations.go b/src/039-nonblocking-channel-operations/nonblocking-channel-operations.go
new file mode 100644
index 0000000..726e0f0
--- /dev/null
+++ b/src/039-nonblocking-channel-operations/nonblocking-channel-operations.go
@@ -0,0 +1,35 @@
+package main
+
+import "fmt"
+
+func main() {
+	messages := make(chan string)
+	signals := make(chan bool)
+
+	// Non-blocking receive.
+	select {
+	case msg := <- messages:
+		fmt.Println("received message", msg)
+	default:
+		fmt.Println("no messages received")
+	}
+
+	// Non-blocking send.
+	msg := "hi"
+	select {
+	case messages <- msg:
+		fmt.Println("sent message", msg)
+	default:
+		fmt.Println("no messages sent")
+	}
+
+	// Non-blocking multi-way select.
+	select {
+	case msg := <- messages:
+		fmt.Println("received message", msg)
+	case sig := <- signals:
+		fmt.Println("received signal", sig)
+	default:
+		fmt.Println("no activity")
+	}
+}
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similarity index 100%
rename from src/039-closing-channels/closing-channels.go
rename to src/040-closing-channels/closing-channels.go
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rename to src/041-timers/timers.go
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diff --git a/tool/index.txt b/tool/index.txt
index c1cffd5..98b30b0 100644
--- a/tool/index.txt
+++ b/tool/index.txt
@@ -43,7 +43,7 @@ timeouts
 scatter-gather
 rate-limiting
 worker-pools
-nonblocking-channel-operations ~
+nonblocking-channel-operations
 closing-channels
 timers
 tickers