diff --git a/node-red/Dockerfile b/node-red/Dockerfile
index 387a948..bc2d59a 100644
--- a/node-red/Dockerfile
+++ b/node-red/Dockerfile
@@ -10,6 +10,7 @@ RUN set -xe \
                           ca-certificates \
                           curl \
                           nodejs \
+                          nodejs-npm \
                           python3 \
                           python3-dev \
     && ln -sf /usr/bin/python3 /usr/bin/python \
diff --git a/node-red/arm/Dockerfile b/node-red/arm/Dockerfile
index c0dd38a..8d58e8b 100644
--- a/node-red/arm/Dockerfile
+++ b/node-red/arm/Dockerfile
@@ -10,6 +10,7 @@ RUN set -xe \
                           ca-certificates \
                           curl \
                           nodejs \
+                          nodejs-npm \
                           python3 \
                           python3-dev \
     && ln -sf /usr/bin/python3 /usr/bin/python \
diff --git a/node-red/patch/36-rpi-gpio.js b/node-red/patch/36-rpi-gpio.js
index 4dadc45..1d2bf08 100644
--- a/node-red/patch/36-rpi-gpio.js
+++ b/node-red/patch/36-rpi-gpio.js
@@ -84,6 +84,7 @@ module.exports = function(RED) {
             node.child.stdout.on('data', function (data) {
                 var d = data.toString().trim().split("\n");
                 for (var i = 0; i < d.length; i++) {
+                    if (d[i] === '') { return; }
                     if (node.running && node.buttonState !== -1 && !isNaN(Number(d[i])) && node.buttonState !== d[i]) {
                         node.send({ topic:"pi/"+node.pin, payload:Number(d[i]) });
                     }