diff --git a/forge-game/src/main/java/forge/game/spellability/AbilitySub.java b/forge-game/src/main/java/forge/game/spellability/AbilitySub.java
index aa9cec63305..d6093763047 100644
--- a/forge-game/src/main/java/forge/game/spellability/AbilitySub.java
+++ b/forge-game/src/main/java/forge/game/spellability/AbilitySub.java
@@ -86,7 +86,8 @@ public final class AbilitySub extends SpellAbility implements java.io.Serializab
         this.setTargetRestrictions(tgt);
 
         api = api0;
-        mapParams.putAll(params0);
+        if (params0 != null)
+            mapParams.putAll(params0);
         effect = api.getSpellEffect();
 
         if (effect instanceof ManaEffect || effect instanceof ManaReflectedEffect) {