diff --git a/libs/core/console.ts b/libs/core/console.ts
index d2754ad3..87ec98a2 100644
--- a/libs/core/console.ts
+++ b/libs/core/console.ts
@@ -46,7 +46,7 @@ namespace console {
     //%
     export function addListener(listener: (text: string) => void) {
         if (!listener) return;
-        if (!listener)
+        if (!listeners)
             listeners = [];
         listeners.push(listener);
     }
diff --git a/libs/core/led.ts b/libs/core/led.ts
index f0dd3850..b317acf4 100644
--- a/libs/core/led.ts
+++ b/libs/core/led.ts
@@ -20,7 +20,7 @@
     //% parts="ledmatrix"
     export function plotBarGraph(value: number, high: number): void {
         const now = input.runningTime();
-        serial.writeLine(value.toString());
+        console.logValue("", value);
         value = Math.abs(value);
 
         // auto-scale "high" is not provided