diff --git a/tools/net/sunrpc/xdrgen/xdr_ast.py b/tools/net/sunrpc/xdrgen/xdr_ast.py
index 9fe7fa688caa..94cdcfb36e77 100644
--- a/tools/net/sunrpc/xdrgen/xdr_ast.py
+++ b/tools/net/sunrpc/xdrgen/xdr_ast.py
@@ -148,6 +148,21 @@ class _XdrVariableLengthOpaque(_XdrDeclaration):
     maxsize: str
     template: str = "variable_length_opaque"
 
+    def max_width(self) -> int:
+        """Return width of type in XDR_UNITS"""
+        return 1 + xdr_quadlen(self.maxsize)
+
+    def symbolic_width(self) -> List:
+        """Return list containing XDR width of type's components"""
+        widths = ["XDR_unsigned_int"]
+        if self.maxsize != "0":
+            widths.append("XDR_QUADLEN(" + self.maxsize + ")")
+        return widths
+
+    def __post_init__(self):
+        max_widths[self.name] = self.max_width()
+        symbolic_widths[self.name] = self.symbolic_width()
+
 
 @dataclass
 class _XdrString(_XdrDeclaration):