diff --git a/lib/util.js b/lib/util.js
index 6c7a4bf..10e513f 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -649,7 +649,7 @@ function isRaspberry(cpuinfo) {
   ];
   if (_rpi_cpuinfo !== null) {
     cpuinfo = _rpi_cpuinfo;
-  } else if (cpuinfo === null) {
+  } else if (cpuinfo === undefined) {
     try {
       cpuinfo = fs.readFileSync('/proc/cpuinfo', { encoding: 'utf8' }).toString().split('\n');
       _rpi_cpuinfo = cpuinfo;
@@ -882,7 +882,7 @@ function decodePiCpuinfo(lines) {
 
   if (_rpi_cpuinfo === null) {
     _rpi_cpuinfo = lines;
-  } else if (lines === null) {
+  } else if (lines === undefined) {
     lines = _rpi_cpuinfo;
   }