diff --git a/code/espurna/sensors/BaseSensor.h b/code/espurna/sensors/BaseSensor.h
index 9f3854f6..e95a644a 100644
--- a/code/espurna/sensors/BaseSensor.h
+++ b/code/espurna/sensors/BaseSensor.h
@@ -46,19 +46,19 @@ class BaseSensor {
         virtual void post() {}
 
         // Descriptive name of the sensor
-        virtual String description() {}
+        virtual String description() = 0;
 
         // Address of the sensor (it could be the GPIO or I2C address)
-        virtual String address(unsigned char index) {}
+        virtual String address(unsigned char index) = 0;
 
         // Descriptive name of the slot # index
-        virtual String slot(unsigned char index) {};
+        virtual String slot(unsigned char index) = 0;
 
         // Type for slot # index
-        virtual unsigned char type(unsigned char index) {}
+        virtual unsigned char type(unsigned char index) = 0;
 
         // Current value for slot # index
-        virtual double value(unsigned char index) {}
+        virtual double value(unsigned char index) = 0;
 
         // Retrieve current instance configuration
         virtual void getConfig(JsonObject& root) {};
diff --git a/code/espurna/sensors/EmonSensor.h b/code/espurna/sensors/EmonSensor.h
index 527a4bda..13647f0d 100644
--- a/code/espurna/sensors/EmonSensor.h
+++ b/code/espurna/sensors/EmonSensor.h
@@ -146,7 +146,7 @@ class EmonSensor : public I2CSensor {
             #endif
         }
 
-        virtual unsigned int readADC(unsigned char channel) {}
+        virtual unsigned int readADC(unsigned char channel) = 0;
 
         void calculateFactors(unsigned char channel) {