diff --git a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2.x.x/src/Pyr0_Piezo_Sensor_V2.x.x.cpp b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2.x.x/src/Pyr0_Piezo_Sensor_V2.x.x.cpp
index a162727..73d9196 100644
--- a/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2.x.x/src/Pyr0_Piezo_Sensor_V2.x.x.cpp
+++ b/firmware/AVR-Source/Pyr0_Piezo_Sensor_v2.x.x/src/Pyr0_Piezo_Sensor_V2.x.x.cpp
@@ -84,7 +84,7 @@ update the voltMeterConstant variable in pP_config.h with the correct value
 
 ------------------------------------------------------------*/
 
-#define PP_VERSION 2.2.1_882a87
+#define PP_VERSION "2.2.1_882a87"
 
 /*  Debug output verbose mode will continuously output sensor readings
     rather than waiting for user input */