diff --git a/IODevice.cpp b/IODevice.cpp
index ea4301f..be26b92 100644
--- a/IODevice.cpp
+++ b/IODevice.cpp
@@ -322,7 +322,7 @@ bool IODevice::checkNoOverlap(VPIN firstPin, uint8_t nPins, uint8_t i2cAddress)
     }
     // Check for overlapping I2C address
     if (i2cAddress && dev->_I2CAddress==i2cAddress) {
-      DIAG(F("WARNING HAL Overlap. i2c Addr 0x%x ignored."),i2cAddress);
+      DIAG(F("WARNING HAL Overlap. i2c Addr 0x%x ignored."),(int)i2cAddress);
       return false;
     } 
   }
diff --git a/IO_AnalogueInputs.h b/IO_AnalogueInputs.h
index 77afc58..a03d90f 100644
--- a/IO_AnalogueInputs.h
+++ b/IO_AnalogueInputs.h
@@ -131,7 +131,7 @@ private:
           break;
       }
     } else { // error status
-      DIAG(F("ADS111x I2C:x%d Error:%d %S"), (int)_I2CAddress, status, I2CManager.getErrorMessage(status));
+      DIAG(F("ADS111x I2C:x%x Error:%d %S"), (int)_I2CAddress, status, I2CManager.getErrorMessage(status));
       _deviceState = DEVSTATE_FAILED;
     }
   }
diff --git a/IO_RotaryEncoder.h b/IO_RotaryEncoder.h
index b4d538c..6de97af 100644
--- a/IO_RotaryEncoder.h
+++ b/IO_RotaryEncoder.h
@@ -104,7 +104,7 @@ private:
   }
   
   void _display() override {
-    DIAG(F("Rotary Encoder I2C:x%x v%d.%d.%d Configured on Vpin:%d-%d %S"), _I2CAddress, _majorVer, _minorVer, _patchVer,
+    DIAG(F("Rotary Encoder I2C:x%x v%d.%d.%d Configured on Vpin:%d-%d %S"), (int)_I2CAddress, _majorVer, _minorVer, _patchVer,
       (int)_firstVpin, _firstVpin+_nPins-1, (_deviceState==DEVSTATE_FAILED) ? F("OFFLINE") : F(""));
   }