diff --git a/lib/Quox/Name.idr b/lib/Quox/Name.idr
index 757f612..9420e36 100644
--- a/lib/Quox/Name.idr
+++ b/lib/Quox/Name.idr
@@ -128,3 +128,11 @@ baseName = idStart <+> many idCont <+> many idEnd
 export
 name : Lexer
 name = baseName <+> many (is '.' <+> baseName)
+
+
+export
+isName : String -> Bool
+isName str =
+  case scan name [] (unpack str) of
+    Just (_, []) => True
+    _            => False
diff --git a/lib/Quox/Syntax/Term/Pretty.idr b/lib/Quox/Syntax/Term/Pretty.idr
index a752e80..ce4adfe 100644
--- a/lib/Quox/Syntax/Term/Pretty.idr
+++ b/lib/Quox/Syntax/Term/Pretty.idr
@@ -115,15 +115,18 @@ prettyCase pi elim r ret arms = do
   arms <- prettyArms arms
   pure $ asep [caseD <++> elim, returnD <++> ret, ofD <++> arms]
 
--- [fixme] put delimiters around tags that aren't simple names
+export
+quoteTag : TagVal -> Doc HL
+quoteTag tag =
+  if isName tag then fromString tag else hcat ["\"", fromString tag, "\""]
+
 export
 prettyTag : TagVal -> Doc HL
-prettyTag t = hl Tag $ "'" <+> fromString t
+prettyTag t = hl Tag $ "'" <+> quoteTag t
 
--- [fixme] put delimiters around tags that aren't simple names
 export
 prettyTagBare : TagVal -> Doc HL
-prettyTagBare t = hl Tag $ fromString t
+prettyTagBare t = hl Tag $ quoteTag t
 
 
 parameters (showSubsts : Bool)
diff --git a/tests/Tests/PrettyTerm.idr b/tests/Tests/PrettyTerm.idr
index 12d1b28..9b1f883 100644
--- a/tests/Tests/PrettyTerm.idr
+++ b/tests/Tests/PrettyTerm.idr
@@ -132,7 +132,6 @@ tests = "pretty printing terms" :- [
     testPrettyT1 [<] [<] (enum []) "{}",
     testPrettyT1 [<] [<] (enum ["a"]) "{a}",
     testPrettyT1 [<] [<] (enum ["aa", "bb", "cc"]) "{aa, bb, cc}",
-    skipWith "todo: quote non-identifiers" $
     testPrettyT1 [<] [<] (enum ["a b c"]) #"{"a b c"}"#
   ],
 
@@ -140,7 +139,6 @@ tests = "pretty printing terms" :- [
     testPrettyT1 [<] [<] (Tag "a") "'a",
     testPrettyT1 [<] [<] (Tag "hello") "'hello",
     testPrettyT1 [<] [<] (Tag "qualified.tag") "'qualified.tag",
-    skipWith "todo: quote non-identifiers" $
     testPrettyT1 [<] [<] (Tag "non-identifier tag") #"'"non-identifier tag""#
   ],