diff --git a/src/ipa/raspberrypi/cam_helper.cpp b/src/ipa/raspberrypi/cam_helper.cpp
index 0ae0baa0..ad344d29 100644
--- a/src/ipa/raspberrypi/cam_helper.cpp
+++ b/src/ipa/raspberrypi/cam_helper.cpp
@@ -17,6 +17,11 @@
 #include "md_parser.hpp"
 
 using namespace RPiController;
+using namespace libcamera;
+
+namespace libcamera {
+LOG_DECLARE_CATEGORY(IPARPI)
+}
 
 static std::map<std::string, CamHelperCreateFunc> cam_helpers;
 
@@ -57,6 +62,19 @@ double CamHelper::Exposure(uint32_t exposure_lines) const
 	return exposure_lines * mode_.line_length / 1000.0;
 }
 
+uint32_t CamHelper::ColourGainCode([[maybe_unused]] double gain) const
+{
+	/*
+	 * This is only used when the sensor has RED/BLUE_BALANCE controls.
+	 * Most do not, so supplying a default is helpful - though no one
+	 * should be calling it.
+	 */
+	LOG(IPARPI, Fatal)
+		<< "Sensor is requesting RED/BLUE gains so a proper "
+		<< "implementation of ColourGainCode must be provided";
+	return 0;
+}
+
 uint32_t CamHelper::GetVBlanking(double &exposure, double minFrameDuration,
 				 double maxFrameDuration) const
 {
diff --git a/src/ipa/raspberrypi/cam_helper.hpp b/src/ipa/raspberrypi/cam_helper.hpp
index 4053a870..a0b6b987 100644
--- a/src/ipa/raspberrypi/cam_helper.hpp
+++ b/src/ipa/raspberrypi/cam_helper.hpp
@@ -26,7 +26,8 @@ namespace RPiController {
 //
 // The ability to convert between number of lines of exposure and actual
 // exposure time, and to convert between the sensor's gain codes and actual
-// gains.
+// gains. Some sensors like to be told the colour (red and blue) gains, so
+// there's a method for converting these to gain codes too.
 //
 // A method to return the number of frames of delay between updating exposure,
 // analogue gain and vblanking, and for the changes to take effect. For many
@@ -72,6 +73,7 @@ public:
 				      double maxFrameDuration) const;
 	virtual uint32_t GainCode(double gain) const = 0;
 	virtual double Gain(uint32_t gain_code) const = 0;
+	virtual uint32_t ColourGainCode(double gain) const;
 	virtual void GetDelays(int &exposure_delay, int &gain_delay,
 			       int &vblank_delay) const;
 	virtual bool SensorEmbeddedDataPresent() const;