diff --git a/src/SCFirstOrderLogic.Tests/SentenceManipulation/VariableManipulation/VariableUnifyingEqualityComparerTests.cs b/src/SCFirstOrderLogic.Tests/SentenceManipulation/VariableManipulation/VariableUnifyingEqualityComparerTests.cs
index 387ea120..bd6f742d 100644
--- a/src/SCFirstOrderLogic.Tests/SentenceManipulation/VariableManipulation/VariableUnifyingEqualityComparerTests.cs
+++ b/src/SCFirstOrderLogic.Tests/SentenceManipulation/VariableManipulation/VariableUnifyingEqualityComparerTests.cs
@@ -23,7 +23,7 @@ public class VariableUnifyingEqualityComparerTests
                 X: P(F(X), F(Y)),
                 Y: P(F(Y), F(X))),
 
-            new( // todo: passes only because the tests standardise the vars as part of tocnf.
+            new(
                 X: P(X, Y, Z),
                 Y: P(Y, Z, X)),
         ])
diff --git a/src/SCFirstOrderLogic/ClauseIndexing/AsyncFeatureVectorIndexDictionaryNode{TFeature,TValue}.cs b/src/SCFirstOrderLogic/ClauseIndexing/AsyncFeatureVectorIndexDictionaryNode{TFeature,TValue}.cs
index 72e6e326..8eba38fb 100644
--- a/src/SCFirstOrderLogic/ClauseIndexing/AsyncFeatureVectorIndexDictionaryNode{TFeature,TValue}.cs
+++ b/src/SCFirstOrderLogic/ClauseIndexing/AsyncFeatureVectorIndexDictionaryNode{TFeature,TValue}.cs
@@ -70,7 +70,7 @@ public async IAsyncEnumerable<KeyValuePair<KeyValuePair<TFeature, int>, IAsyncFe
     /// <inheritdoc/>
     public ValueTask<IAsyncFeatureVectorIndexNode<TFeature, TValue>> GetOrAddChildAsync(KeyValuePair<TFeature, int> vectorComponent)
     {
-        IAsyncFeatureVectorIndexNode<TFeature, TValue> node = new AsyncFeatureVectorIndexDictionaryNode<TFeature, TValue>();
+        IAsyncFeatureVectorIndexNode<TFeature, TValue> node = new AsyncFeatureVectorIndexDictionaryNode<TFeature, TValue>(childrenByVectorComponent.Comparer);
         if (!childrenByVectorComponent.TryAdd(vectorComponent, node))
         {
             node = childrenByVectorComponent[vectorComponent];
diff --git a/src/SCFirstOrderLogic/ClauseIndexing/FeatureVectorIndexDictionaryNode{TFeature,TValue}.cs b/src/SCFirstOrderLogic/ClauseIndexing/FeatureVectorIndexDictionaryNode{TFeature,TValue}.cs
index 9a1eafc0..a03f1065 100644
--- a/src/SCFirstOrderLogic/ClauseIndexing/FeatureVectorIndexDictionaryNode{TFeature,TValue}.cs
+++ b/src/SCFirstOrderLogic/ClauseIndexing/FeatureVectorIndexDictionaryNode{TFeature,TValue}.cs
@@ -55,7 +55,7 @@ public IFeatureVectorIndexNode<TFeature, TValue> GetOrAddChild(KeyValuePair<TFea
     {
         if (!childrenByVectorComponent.TryGetValue(vectorComponent, out var node))
         {
-            node = new FeatureVectorIndexDictionaryNode<TFeature, TValue>();
+            node = new FeatureVectorIndexDictionaryNode<TFeature, TValue>(childrenByVectorComponent.Comparer);
             childrenByVectorComponent.Add(vectorComponent, node);
         }