diff --git a/ats-format.cabal b/ats-format.cabal
--- a/ats-format.cabal
+++ b/ats-format.cabal
@@ -1,5 +1,5 @@
 name:                ats-format
-version:             0.1.0.14
+version:             0.1.0.15
 synopsis:            A source-code formatter for ATS
 description:         An opinionated source-code formatter for ATS (http://www.ats-lang.org/).
 homepage:            https://hub.darcs.net/vmchale/ats-format#readme
diff --git a/man/atsfmt.1 b/man/atsfmt.1
--- a/man/atsfmt.1
+++ b/man/atsfmt.1
@@ -1,4 +1,4 @@
-.\" Automatically generated by Pandoc 2.0.5
+.\" Automatically generated by Pandoc 2.0.6
 .\"
 .TH "atsfmt (1)" "" "" "" ""
 .hy
diff --git a/src/Language/ATS/Parser.y b/src/Language/ATS/Parser.y
--- a/src/Language/ATS/Parser.y
+++ b/src/Language/ATS/Parser.y
@@ -35,6 +35,7 @@
     fn { Keyword $$ KwFn }
     castfn { Keyword $$ KwCastfn }
     prfun { Keyword $$ KwPrfun }
+    prfn { Keyword $$ KwPrfn }
     fnx { Keyword $$ KwFnx }
     and { Keyword $$ KwAnd }
     lambda { Keyword $$ KwLambda }
@@ -491,6 +492,7 @@
 -- | Function declaration
 FunDecl : fun PreFunction { [ Func $1 (Fun $2) ] }
         | prfun PreFunction { [ Func $1 (PrFun $2) ] }
+        | prfn PreFunction { [ Func $1 (PrFn $2) ] }
         | fnx PreFunction { [ Func $1 (Fnx $2) ] }
         | castfn PreFunction { [ Func $1 (CastFn $2) ] }
         | fn PreFunction { [ Func $1 (Fn $2) ] }
@@ -500,6 +502,7 @@
         | extern fnx PreFunction eq {% Left $ Expected $1 "Declaration" "Function body" }
         | extern praxi PreFunction eq {% Left $ Expected $1 "Declaration" "Function body" }
         | extern prfun PreFunction eq {% Left $ Expected $1 "Declaration" "Function body" }
+        | extern prfn PreFunction eq {% Left $ Expected $1 "Declaration" "Function body" }
         | lambda {% Left $ Expected $1 "Function declaration" "lam" }
         | llambda {% Left $ Expected $1 "Function declaration" "llam" }
 
diff --git a/src/Language/ATS/PrettyPrint.hs b/src/Language/ATS/PrettyPrint.hs
--- a/src/Language/ATS/PrettyPrint.hs
+++ b/src/Language/ATS/PrettyPrint.hs
@@ -443,6 +443,7 @@
     pretty (Func _ (And pref))   = "and" </> pretty pref
     pretty (Func _ (Praxi pref)) = "praxi" </> pretty pref
     pretty (Func _ (PrFun pref)) = "prfun" </> pretty pref
+    pretty (Func _ (PrFn pref))  = "prfn" </> pretty pref
     pretty (Extern _ d)          = "extern" <$> pretty d
     pretty (Define s)            = string s
     pretty (DataProp _ s as ls)  = "dataprop" <+> string s <> prettyArgs as <+> "=" <$> prettyDL ls