diff --git a/src/main/java/org/nwapw/abacus/fx/AbacusController.java b/src/main/java/org/nwapw/abacus/fx/AbacusController.java
index d21c034..c765a8e 100644
--- a/src/main/java/org/nwapw/abacus/fx/AbacusController.java
+++ b/src/main/java/org/nwapw/abacus/fx/AbacusController.java
@@ -1,5 +1,7 @@
 package org.nwapw.abacus.fx;
 
+import javafx.collections.FXCollections;
+import javafx.collections.ObservableList;
 import javafx.fxml.FXML;
 import javafx.scene.control.Button;
 import javafx.scene.control.TextField;
@@ -20,11 +22,14 @@ public class AbacusController {
     @FXML
     private Button inputButton;
 
+    private ObservableList<HistoryModel> historyData;
+
     private Abacus abacus;
 
     @FXML
     public void initialize(){
         abacus = new Abacus();
+        historyData = FXCollections.observableArrayList();
     }
 
     @FXML
@@ -37,7 +42,7 @@ public class AbacusController {
             return;
         }
         NumberInterface evaluatedNumber = abacus.evaluateTree(constructedTree);
-        if(constructedTree == null){
+        if(evaluatedNumber == null){
             outputText.setText(ERR_EVAL);
             inputButton.setDisable(false);
             return;
diff --git a/src/main/java/org/nwapw/abacus/fx/HistoryModel.java b/src/main/java/org/nwapw/abacus/fx/HistoryModel.java
new file mode 100644
index 0000000..2a267b5
--- /dev/null
+++ b/src/main/java/org/nwapw/abacus/fx/HistoryModel.java
@@ -0,0 +1,42 @@
+package org.nwapw.abacus.fx;
+
+import javafx.beans.property.SimpleStringProperty;
+import javafx.beans.property.StringProperty;
+
+public class HistoryModel {
+
+    private final StringProperty input;
+    private final StringProperty parsed;
+    private final StringProperty output;
+
+    public HistoryModel(String input, String parsed, String output){
+        this.input = new SimpleStringProperty();
+        this.parsed = new SimpleStringProperty();
+        this.output = new SimpleStringProperty();
+        this.input.setValue(input);
+        this.parsed.setValue(parsed);
+        this.output.setValue(output);
+    }
+
+    public StringProperty inputProperty() {
+        return input;
+    }
+    public String getInput() {
+        return input.get();
+    }
+
+    public StringProperty parsedProperty() {
+        return parsed;
+    }
+    public String getParsed() {
+        return parsed.get();
+    }
+
+    public StringProperty outputProperty() {
+        return output;
+    }
+    public String getOutput() {
+        return output.get();
+    }
+
+}