diff --git a/src/main/java/forge/deck/DeckFormat.java b/src/main/java/forge/deck/DeckFormat.java
index d720fb2f15e..175b920ffef 100644
--- a/src/main/java/forge/deck/DeckFormat.java
+++ b/src/main/java/forge/deck/DeckFormat.java
@@ -116,6 +116,10 @@ public enum DeckFormat {
 
     @SuppressWarnings("incomplete-switch")
     public String getDeckConformanceProblem(Deck deck) {
+        if(deck == null) {
+            return "is not selected";
+        }
+
         // That's really a bad dependence
         if (!Singletons.getModel().getPreferences().getPrefBoolean(FPref.ENFORCE_DECK_LEGALITY)) {
             return null;
diff --git a/src/main/java/forge/gui/home/sanctioned/CSubmenuConstructed.java b/src/main/java/forge/gui/home/sanctioned/CSubmenuConstructed.java
index 2a6574906da..31a7e7f82b9 100644
--- a/src/main/java/forge/gui/home/sanctioned/CSubmenuConstructed.java
+++ b/src/main/java/forge/gui/home/sanctioned/CSubmenuConstructed.java
@@ -92,14 +92,22 @@ public enum CSubmenuConstructed implements ICDoc {
         view.getCbRemoveSmall().setSelected(prefs.getPrefBoolean(FPref.DECKGEN_NOSMALL));
     }
 
-    /** @param gameType 
-     * @param lists0 &emsp; {@link java.util.List}<{@link javax.swing.JList}> */
+    /**
+     *
+     * @param gameType
+     */
     private void startGame(final GameType gameType) {
         Deck humanDeck = VSubmenuConstructed.SINGLETON_INSTANCE.getDcHuman().getDeck();
+        String humanDeckErrorMessage = gameType.getDecksFormat().getDeckConformanceProblem(humanDeck);
+        if (null != humanDeckErrorMessage) {
+            JOptionPane.showMessageDialog(null, "Your deck " + humanDeckErrorMessage, "Invalid deck", JOptionPane.ERROR_MESSAGE);
+            return;
+        }
 
-        String errorMessage = gameType.getDecksFormat().getDeckConformanceProblem(humanDeck);
-        if (null != errorMessage) {
-            JOptionPane.showMessageDialog(null, "Your deck " + errorMessage, "Invalid deck", JOptionPane.ERROR_MESSAGE);
+        Deck aiDeck = VSubmenuConstructed.SINGLETON_INSTANCE.getDcAi().getDeck();
+        String aiDeckErrorMessage = gameType.getDecksFormat().getDeckConformanceProblem(aiDeck);
+        if (null != aiDeckErrorMessage) {
+            JOptionPane.showMessageDialog(null, "AI deck " + aiDeckErrorMessage, "Invalid deck", JOptionPane.ERROR_MESSAGE);
             return;
         }