diff --git a/apps/graph/storage_cartesian_function_store.cpp b/apps/graph/storage_cartesian_function_store.cpp
index be6649b9a..258980c94 100644
--- a/apps/graph/storage_cartesian_function_store.cpp
+++ b/apps/graph/storage_cartesian_function_store.cpp
@@ -28,7 +28,7 @@ Ion::Storage::Record::ErrorStatus StorageCartesianFunctionStore::addEmptyModel()
   return error;
 }
 
-void StorageCartesianFunctionStore::privateSetMemoizedModelAtIndex(int cacheIndex, Ion::Storage::Record record) const {
+void StorageCartesianFunctionStore::setMemoizedModelAtIndex(int cacheIndex, Ion::Storage::Record record) const {
   assert(cacheIndex >= 0 && cacheIndex < k_maxNumberOfMemoizedModels);
   m_functions[cacheIndex] = StorageCartesianFunction(record);
 }
diff --git a/apps/graph/storage_cartesian_function_store.h b/apps/graph/storage_cartesian_function_store.h
index 1d5c080a9..3637109de 100644
--- a/apps/graph/storage_cartesian_function_store.h
+++ b/apps/graph/storage_cartesian_function_store.h
@@ -19,7 +19,7 @@ public:
 private:
   Ion::Storage::Record::ErrorStatus addEmptyModel() override;
   const char * modelExtension() const override { return Shared::GlobalContext::funcExtension; }
-  void privateSetMemoizedModelAtIndex(int cacheIndex, Ion::Storage::Record record) const override;
+  void setMemoizedModelAtIndex(int cacheIndex, Ion::Storage::Record record) const override;
   void moveMemoizedModel(int previousIndex, int nextIndex) const override;
   Shared::StorageExpressionModel * memoizedModelAtIndex(int cacheIndex) const override;
   mutable Shared::StorageCartesianFunction m_functions[k_maxNumberOfMemoizedModels];
diff --git a/apps/shared/storage_expression_model_store.cpp b/apps/shared/storage_expression_model_store.cpp
index 6521b390a..8f2cb6116 100644
--- a/apps/shared/storage_expression_model_store.cpp
+++ b/apps/shared/storage_expression_model_store.cpp
@@ -25,16 +25,18 @@ int StorageExpressionModelStore::numberOfDefinedModels() const {
 }
 
 StorageExpressionModel * StorageExpressionModelStore::modelAtIndex(int i) const {
+  /* If the model index asked is out of the range of the memoized index, we
+   * translate the memoized models to include the model i at the closest
+   * extremity of the array. */
   if (i >= m_firstMemoizedModelIndex+k_maxNumberOfMemoizedModels || i < m_firstMemoizedModelIndex) {
-    // Change range of layout memoization
     int deltaIndex = i >= m_firstMemoizedModelIndex + k_maxNumberOfMemoizedModels ? i - k_maxNumberOfMemoizedModels + 1 - m_firstMemoizedModelIndex : i - m_firstMemoizedModelIndex;
     // Translate memoized models
     for (int i = 0; i < k_maxNumberOfMemoizedModels-1; i++) {
       int j = deltaIndex + i;
       if (j >= 0 && j < k_maxNumberOfMemoizedModels) {
-        m_memoizedModelChecksum[i] = m_memoizedModelChecksum[j];
         moveMemoizedModel(i, j);
       } else {
+        // Fill new models with empty records
         Ion::Storage::Record emptyRecord;
         setMemoizedModelAtIndex(i, emptyRecord);
       }
@@ -42,10 +44,15 @@ StorageExpressionModel * StorageExpressionModelStore::modelAtIndex(int i) const
     m_firstMemoizedModelIndex += deltaIndex;
   }
   assert(i-m_firstMemoizedModelIndex < k_maxNumberOfMemoizedModels);
-  Ion::Storage::Record record = Ion::Storage::sharedStorage()->recordWithExtensionAtIndex(modelExtension(), i);
-  // Storage might have changed since last call
-  if (memoizedModelAtIndex(i-m_firstMemoizedModelIndex)->isNull() || m_memoizedModelChecksum[i-m_firstMemoizedModelIndex] != record.checksum()) {
+  uint32_t currentStorageChecksum = Ion::Storage::sharedStorage()->checksum();
+  /* We have to build a new model if:
+   * - the model has never been created
+   * - Storage changed since last built. For instance, if f(x) = A+x, if A
+   *   changes, we need to unmemoize f. */
+  if (memoizedModelAtIndex(i-m_firstMemoizedModelIndex)->isNull() || currentStorageChecksum != m_storageChecksum) {
+    Ion::Storage::Record record = Ion::Storage::sharedStorage()->recordWithExtensionAtIndex(modelExtension(), i);
     setMemoizedModelAtIndex(i-m_firstMemoizedModelIndex, record);
+    m_storageChecksum = currentStorageChecksum;
   }
   return memoizedModelAtIndex(i-m_firstMemoizedModelIndex);
 }
@@ -87,9 +94,4 @@ void StorageExpressionModelStore::tidy() {
   }
 }
 
-void StorageExpressionModelStore::setMemoizedModelAtIndex(int cacheIndex, Ion::Storage::Record record) const {
-  m_memoizedModelChecksum[cacheIndex] = record.isNull() ? 0 : record.checksum();
-  privateSetMemoizedModelAtIndex(cacheIndex, record);
-}
-
 }
diff --git a/apps/shared/storage_expression_model_store.h b/apps/shared/storage_expression_model_store.h
index 5b5c63cd2..496514e14 100644
--- a/apps/shared/storage_expression_model_store.h
+++ b/apps/shared/storage_expression_model_store.h
@@ -31,11 +31,12 @@ protected:
   constexpr static int k_maxNumberOfMemoizedModels = 5;
 private:
   virtual const char * modelExtension() const = 0;
-  // Memoization of k_maxNumberOfMemoizedModels consecutive models
+  /* Memoization of k_maxNumberOfMemoizedModels consecutive models:
+   * stores memoize k_maxNumberOfMemoizedModels consecutive models from the
+   * m_firstMemoizedModelIndex. */
   mutable int m_firstMemoizedModelIndex;
-  mutable uint32_t m_memoizedModelChecksum[k_maxNumberOfMemoizedModels];
-  void setMemoizedModelAtIndex(int cacheIndex, Ion::Storage::Record) const;
-  virtual void privateSetMemoizedModelAtIndex(int cacheIndex, Ion::Storage::Record record) const = 0;
+  mutable uint32_t m_storageChecksum;
+  virtual void setMemoizedModelAtIndex(int cacheIndex, Ion::Storage::Record) const = 0;
   virtual void moveMemoizedModel(int previousIndex, int nextIndex) const = 0;
   virtual StorageExpressionModel * memoizedModelAtIndex(int cacheIndex) const = 0;
 };