diff --git a/src/Init/SizeOf.lean b/src/Init/SizeOf.lean
index d81daaa75c..5658145c41 100644
--- a/src/Init/SizeOf.lean
+++ b/src/Init/SizeOf.lean
@@ -35,10 +35,16 @@ deriving instance SizeOf for Option
 deriving instance SizeOf for List
 deriving instance SizeOf for Array
 deriving instance SizeOf for Subtype
-deriving instance SizeOf for Except
-deriving instance SizeOf for EStateM.Result
+deriving instance SizeOf for Fin
+deriving instance SizeOf for USize
+deriving instance SizeOf for UInt8
+deriving instance SizeOf for UInt16
+deriving instance SizeOf for UInt32
+deriving instance SizeOf for UInt64
 deriving instance SizeOf for Char
 deriving instance SizeOf for String
 deriving instance SizeOf for Substring
+deriving instance SizeOf for Except
+deriving instance SizeOf for EStateM.Result
 deriving instance SizeOf for Lean.Name
 deriving instance SizeOf for Lean.Syntax