diff --git a/src/TachSensor.cpp b/src/TachSensor.cpp
index d2afba7..30ab202 100644
--- a/src/TachSensor.cpp
+++ b/src/TachSensor.cpp
@@ -228,7 +228,7 @@
 
         gpioFd.assign(gpioLineFd);
     }
-    catch (std::system_error&)
+    catch (const std::system_error&)
     {
         std::cerr << "Error reading gpio: " << gpioName << "\n";
         status = false;