diff --git a/src/main/java/ca/spottedleaf/dataconverter/types/nbt/NBTMapType.java b/src/main/java/ca/spottedleaf/dataconverter/types/nbt/NBTMapType.java
index 70e9708..ceb6b9b 100644
--- a/src/main/java/ca/spottedleaf/dataconverter/types/nbt/NBTMapType.java
+++ b/src/main/java/ca/spottedleaf/dataconverter/types/nbt/NBTMapType.java
@@ -419,8 +419,11 @@ public ListType getListUnchecked(final String key, final ListType dfl) {
         final Object tag = this.map.get(key);
         if (tag instanceof NBTListType l)
             return l;
-        if (tag instanceof ListBinaryTag)
-            return new NBTListType((ListBinaryTag) tag);
+        if (tag instanceof ListBinaryTag) {
+            var map = new NBTListType((ListBinaryTag) tag);
+            this.map.put(key, map);
+            return map;
+        }
         return dfl;
     }
 
@@ -439,8 +442,11 @@ public MapType<String> getMap(final String key, final MapType dfl) {
         final Object tag = this.map.get(key);
         if (tag instanceof NBTMapType m)
             return m;
-        if (tag instanceof CompoundBinaryTag)
-            return new NBTMapType((CompoundBinaryTag) tag);
+        if (tag instanceof CompoundBinaryTag) {
+            var map = new NBTMapType((CompoundBinaryTag) tag);
+            this.map.put(key, map);
+            return map;
+        }
         return dfl;
     }