diff --git a/prototype/Doubt/Diff.swift b/prototype/Doubt/Diff.swift
index b47eccdcd..bb6d348da 100644
--- a/prototype/Doubt/Diff.swift
+++ b/prototype/Doubt/Diff.swift
@@ -31,8 +31,8 @@ public enum Diff: Comparable, CustomDebugStringConvertible, CustomDocConvertible
 		case let .Copy(a):
 			return a.doc
 		case let .ByKey(a, b):
-			return a.keys.sort().map { Doc($0) <> Doc(":") <+> Doc(a[$0]!) }.stack().bracket("{-", "-}")
-				<> b.keys.sort().map { Doc($0) <> Doc(":") <+> Doc(b[$0]!) }.stack().bracket("{+", "+}")
+			return a.keys.sort().map { Doc($0) <> Doc(":") <+> Doc(a[$0]!) }.joinWithSeparator(",").bracket("{-", "-}")
+				<> b.keys.sort().map { Doc($0) <> Doc(":") <+> Doc(b[$0]!) }.joinWithSeparator(",").bracket("{+", "+}")
 		}
 	}
 
diff --git a/prototype/Doubt/Syntax.swift b/prototype/Doubt/Syntax.swift
index c140b0bcd..fa2fe1ccf 100644
--- a/prototype/Doubt/Syntax.swift
+++ b/prototype/Doubt/Syntax.swift
@@ -79,7 +79,7 @@ public enum Syntax<Recur, A>: CustomDebugStringConvertible, CustomDocConvertible
 		case let .Leaf(n):
 			return Doc(n)
 		case let .Branch(vs):
-			return vs.map(Doc.init).stack().bracket("{", "}")
+			return vs.map(Doc.init).joinWithSeparator(",").bracket("{", "}")
 		}
 	}
 }