diff --git a/pinot-core/src/main/java/org/apache/pinot/core/function/scalar/SketchFunctions.java b/pinot-core/src/main/java/org/apache/pinot/core/function/scalar/SketchFunctions.java
index 4bd951d3c297..74e35e8bb74a 100644
--- a/pinot-core/src/main/java/org/apache/pinot/core/function/scalar/SketchFunctions.java
+++ b/pinot-core/src/main/java/org/apache/pinot/core/function/scalar/SketchFunctions.java
@@ -502,6 +502,7 @@ public static byte[] toULL(@Nullable Object input, int p) {
    *
    * This adds the P value into the serialized byte stream, so it can be used easily
    */
+  @ScalarFunction
   public static byte[] fromULL(byte[] input) {
     UltraLogLog ull = UltraLogLog.wrap(input);
     return ObjectSerDeUtils.ULTRA_LOG_LOG_OBJECT_SER_DE.serialize(ull);