diff --git a/src/ifcopenshell-python/ifcopenshell/validate.py b/src/ifcopenshell-python/ifcopenshell/validate.py
index e3391add24..92e3681270 100644
--- a/src/ifcopenshell-python/ifcopenshell/validate.py
+++ b/src/ifcopenshell-python/ifcopenshell/validate.py
@@ -597,6 +597,25 @@ def validate_guid(guid: str) -> Union[str, None]:
         return "Couldn't decompress guid, it's not base64 encoded."
     return None
 
+def to_string_header_entity(header_entity):
+    """Recreate IFC header string representation, like FILE_NAME(...)"""
+    def format_value(val):
+        if isinstance(val, str):
+            return f"'{val}'"
+        elif isinstance(val, tuple):
+            return "(" + ",".join(format_value(v) for v in val) + ")"
+        return str(val)
+
+    # Prefer native .toString() if available (native IfcOpenShell wrapper)
+    if hasattr(header_entity, 'toString'):
+        return header_entity.toString()
+
+    if hasattr(header_entity, '_fields'):
+        values = [format_value(getattr(header_entity, f)) for f in header_entity._fields]
+    else:
+        raise TypeError(f"Cannot stringify header_entity of type {type(header_entity)}")
+
+    return f"{type(header_entity).__name__.upper()}({','.join(values)})"
 
 def validate_ifc_header(f: Union[ifcopenshell.file, ifcopenshell.simple_spf.file], logger: Logger) -> None:
     if type(f) is ifcopenshell.file:
@@ -613,7 +632,7 @@ def validate_ifc_header(f: Union[ifcopenshell.file, ifcopenshell.simple_spf.file
                 "Attribute '%s' has invalid type:\n"
                 "    Expected: %s\n    Current value type: %s\n"
             ),
-            (s := header_entity.toString()),
+            (s := to_string_header_entity(header_entity)),
             annotate_inst_attr_pos(header_entity, index, s),
             name,
             expected_type,