diff --git a/Changes.md b/Changes.md
index 19ce752663..e822003d23 100644
--- a/Changes.md
+++ b/Changes.md
@@ -12,6 +12,7 @@ Fixes
 - Plug : Fixed bug which meant nodes would fail to update if a newly created plug was renamed before being parented to the node.
 - Metadata : Fixed handling of exceptions thrown from value functions implemented in Python. These are now correctly translated into C++ exceptions.
 - Cycles, OSLObject, OSLImage, Expression : Fixed crashes when using OSL on macOS.
+- Cycles : Use ccl::DeviceInfo's 'num' entry instead of typeIndex for the index representation of the GPU device number.
 
 1.6.16.0 (relative to 1.6.15.0)
 ========
diff --git a/python/GafferCyclesUI/CyclesOptionsUI.py b/python/GafferCyclesUI/CyclesOptionsUI.py
index a05748867e..6f8f9b45c1 100644
--- a/python/GafferCyclesUI/CyclesOptionsUI.py
+++ b/python/GafferCyclesUI/CyclesOptionsUI.py
@@ -239,10 +239,10 @@ def __registerDevicePresets() :
 		typeIndices[device["type"]] += 1
 
 		presetNames.append( "{}/{}".format( device["type"], device["description"] ) )
-		presetValues.append( "{}:{:02}".format( device["type"], typeIndex ) )
+		presetValues.append( "{}:{:02}".format( device["type"], device["num"].value ) )
 
 		presetNames.append( "{}/{} + CPU".format( device["type"], device["description"] ) )
-		presetValues.append( "CPU {}:{:02}".format( device["type"], typeIndex ) )
+		presetValues.append( "CPU {}:{:02}".format( device["type"], device["num"].value ) )
 
 	for deviceType, count in typeIndices.items() :
 
diff --git a/src/GafferCycles/IECoreCyclesPreview/Renderer.cpp b/src/GafferCycles/IECoreCyclesPreview/Renderer.cpp
index 6ee574b2a2..78c2741722 100644
--- a/src/GafferCycles/IECoreCyclesPreview/Renderer.cpp
+++ b/src/GafferCycles/IECoreCyclesPreview/Renderer.cpp
@@ -2358,7 +2358,7 @@ ccl::DeviceInfo matchingDevices( const std::string &pattern, int threads, bool b
 	{
 		const string typeString = ccl::Device::string_from_type( device.type );
 		const int typeIndex = typeIndices[device.type]++;
-		const string name = fmt::format( "{}:{:02}", typeString, typeIndex );
+		const string name = fmt::format( "{}:{:02}", typeString, device.num );
 		if(
 			// e.g. "CPU" matches the first CPU device.
 			( typeIndex == 0 && StringAlgo::matchMultiple( typeString, pattern ) ) ||