diff --git a/src/main/java/org/nwapw/abacus/number/NumberInterface.java b/src/main/java/org/nwapw/abacus/number/NumberInterface.java
index 34edfcc..c534225 100755
--- a/src/main/java/org/nwapw/abacus/number/NumberInterface.java
+++ b/src/main/java/org/nwapw/abacus/number/NumberInterface.java
@@ -240,6 +240,7 @@ public abstract class NumberInterface {
      * @param toClass the class to promote to.
      * @return the resulting new instance.
      */
+    @Deprecated
     protected abstract NumberInterface promoteToInternal(Class<? extends NumberInterface> toClass);
 
     /**
@@ -250,6 +251,7 @@ public abstract class NumberInterface {
      * @param toClass the class to promote to.
      * @return the resulting new instance.
      */
+    @Deprecated
     public final NumberInterface promoteTo(Class<? extends NumberInterface> toClass) {
         checkInterrupted();
         return promoteToInternal(toClass);