diff --git a/src/CPUSensor.cpp b/src/CPUSensor.cpp
index 1b04299..0ec4bf5 100644
--- a/src/CPUSensor.cpp
+++ b/src/CPUSensor.cpp
@@ -204,7 +204,7 @@
     responseStream.clear();
     inputDev.close();
     int fd = open(path.c_str(), O_RDONLY);
-    if (fd <= 0)
+    if (fd < 0)
     {
         return; // we're no longer valid
     }