diff --git a/com.unity.render-pipelines.high-definition/CHANGELOG.md b/com.unity.render-pipelines.high-definition/CHANGELOG.md
index d25e193a583..859d0a18cd1 100644
--- a/com.unity.render-pipelines.high-definition/CHANGELOG.md
+++ b/com.unity.render-pipelines.high-definition/CHANGELOG.md
@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed ShaderGraph Decal material not showing exposed properties.
 - Fixed wrong coat normal space in shader graph
 - Fixed issue with faulty shadow transition when view is close to an object under some aspect ratio conditions
+- Fixed NullPointerException when baking probes from the lighting window (case 1289680)
 
 ### Changed
 - Removed the material pass probe volumes evaluation mode.
diff --git a/com.unity.render-pipelines.high-definition/Editor/Lighting/Reflection/HDBakedReflectionSystem.cs b/com.unity.render-pipelines.high-definition/Editor/Lighting/Reflection/HDBakedReflectionSystem.cs
index 24c687329b2..a07b3fd9edd 100644
--- a/com.unity.render-pipelines.high-definition/Editor/Lighting/Reflection/HDBakedReflectionSystem.cs
+++ b/com.unity.render-pipelines.high-definition/Editor/Lighting/Reflection/HDBakedReflectionSystem.cs
@@ -322,7 +322,7 @@ IScriptableBakedReflectionSystemStageNotifier handle
                 // == 5. ==
 
                 // Create new baked state array
-                var targetSize = m_HDProbeBakedStates.Length + addCount - remCount;
+                var targetSize = m_HDProbeBakedStates.Length - remCount + toBakeIndicesList.Count;
                 var targetBakedStates = stackalloc HDProbeBakedState[targetSize];
                 // Copy baked state that are not removed
                 var targetI = 0;
@@ -330,12 +330,14 @@ IScriptableBakedReflectionSystemStageNotifier handle
                 {
                     if (CoreUnsafeUtils.IndexOf(remIndices, remCount, i) != -1)
                         continue;
+                    Assert.IsTrue(targetI < targetSize);
                     targetBakedStates[targetI++] = m_HDProbeBakedStates[i];
                 }
                 // Add new baked states
                 for (int i = 0; i < toBakeIndicesList.Count; ++i)
                 {
                     var state = states[toBakeIndicesList.GetUnchecked(i)];
+                    Assert.IsTrue(targetI < targetSize);
                     targetBakedStates[targetI++] = new HDProbeBakedState
                     {
                         instanceID = state.instanceID,