diff --git a/lib/trino-plugin-toolkit/src/main/java/io/trino/plugin/base/metrics/TDigestHistogram.java b/lib/trino-plugin-toolkit/src/main/java/io/trino/plugin/base/metrics/TDigestHistogram.java
index 6567de93734a..0c06744b3f3b 100644
--- a/lib/trino-plugin-toolkit/src/main/java/io/trino/plugin/base/metrics/TDigestHistogram.java
+++ b/lib/trino-plugin-toolkit/src/main/java/io/trino/plugin/base/metrics/TDigestHistogram.java
@@ -66,10 +66,15 @@ public synchronized TDigest getDigest()
     public TDigestHistogram mergeWith(TDigestHistogram other)
     {
         TDigest result = getDigest();
-        result.mergeWith(other.getDigest());
+        other.mergeTo(result);
         return new TDigestHistogram(result);
     }
 
+    private synchronized void mergeTo(TDigest digest)
+    {
+        digest.mergeWith(this.digest);
+    }
+
     @Override
     @JsonProperty
     public synchronized long getTotal()