diff --git a/prototype/doubt-difftool/main.swift b/prototype/doubt-difftool/main.swift
index 115447e0b..e9ac2424b 100644
--- a/prototype/doubt-difftool/main.swift
+++ b/prototype/doubt-difftool/main.swift
@@ -7,7 +7,7 @@ func readFile(path: String) -> String? {
 	return data as String?
 }
 
-typealias Term = Cofree<String, Range<Int>>
+typealias Term = Cofree<String, Info>
 
 struct Info: Categorizable, CustomJSONConvertible, Equatable {
 	let range: Range<Int>
@@ -64,7 +64,7 @@ func termWithInput(string: String) -> Term? {
 				}
 			} (root, "program")
 			.map { node, category in
-				node.range
+				Info(range: node.range, categories: [ category ])
 			}
 	}
 }
@@ -82,10 +82,10 @@ if let aString = arguments[1].flatMap(readFile), bString = arguments[2].flatMap(
 		let JSON: Doubt.JSON = [
 			"before": .String(aString),
 			"after": .String(bString),
-			"diff": diff.JSON(pure: { $0.JSON { $0.JSON(annotation: range, leaf: Doubt.JSON.String) } }, leaf: Doubt.JSON.String, annotation: {
+			"diff": diff.JSON(pure: { $0.JSON { $0.JSON(annotation: { $0.range.JSON }, leaf: Doubt.JSON.String) } }, leaf: Doubt.JSON.String, annotation: {
 				[
-					"before": range($0),
-					"after": range($1),
+					"before": $0.range.JSON,
+					"after": $1.range.JSON,
 				]
 			}),
 		]