diff --git a/eo-runtime/src/main/java/org/eolang/PhDefault.java b/eo-runtime/src/main/java/org/eolang/PhDefault.java
index aa70463118..e9a1aa743f 100644
--- a/eo-runtime/src/main/java/org/eolang/PhDefault.java
+++ b/eo-runtime/src/main/java/org/eolang/PhDefault.java
@@ -268,7 +268,10 @@ public byte[] delta() {
             bytes = this.take(Attr.PHI).delta();
         } else {
             throw new ExFailure(
-                "There's no data in the object, can't take it"
+                String.format(
+                    "There's no data in the object of %s",
+                    this.forma()
+                )
             );
         }
         return bytes;