diff --git a/bower.json b/bower.json
index c7ecb82..358297e 100644
--- a/bower.json
+++ b/bower.json
@@ -16,16 +16,16 @@
     "package.json"
   ],
   "dependencies": {
-    "purescript-datetime": "^6.0.0",
+    "purescript-datetime": "^6.1.0",
     "purescript-fixed-points": "^7.0.0",
     "purescript-lists": "^7.0.0",
-    "purescript-numbers": "^9.0.0",
-    "purescript-parsing": "^9.0.0",
-    "purescript-prelude": "^6.0.0",
+    "purescript-numbers": "^9.0.1",
+    "purescript-parsing": "^10.2.0",
+    "purescript-prelude": "^6.0.1",
     "purescript-transformers": "^6.0.0"
   },
   "devDependencies": {
-    "purescript-aff": "^7.0.0",
+    "purescript-aff": "^7.1.0",
     "purescript-assert": "^6.0.0",
     "purescript-console": "^6.0.0",
     "purescript-effect": "^4.0.0"
diff --git a/src/Data/Formatter/DateTime.purs b/src/Data/Formatter/DateTime.purs
index 84c105b..ec0ec15 100644
--- a/src/Data/Formatter/DateTime.purs
+++ b/src/Data/Formatter/DateTime.purs
@@ -92,7 +92,7 @@ printFormatterCommand = case _ of
   DayOfMonthTwoDigits -> "DD"
   DayOfMonth -> "D"
   UnixTimestamp -> "X"
-  DayOfWeek -> "E"
+  DayOfWeek -> "d"
   DayOfWeekName -> "dddd"
   DayOfWeekNameShort -> "ddd"
   Hours24 -> "HH"
@@ -111,7 +111,7 @@ printFormatterCommand = case _ of
   needsEscaping = CU.toCharArray >>> Array.any (flip Array.elem formatCharacters)
 
 formatCharacters :: Array Char
-formatCharacters = CU.toCharArray "YMDEHhamsS"
+formatCharacters = CU.toCharArray "YMDXdHhamsS"
 
 printFormatter :: Formatter -> String
 printFormatter = foldMap printFormatterCommand
@@ -146,10 +146,10 @@ formatterCommandParser =
     , Tuple "MM" MonthTwoDigits
     , Tuple "DD" DayOfMonthTwoDigits
     , Tuple "D" DayOfMonth
-    , Tuple "E" DayOfWeek
     , Tuple "X" UnixTimestamp
     , Tuple "dddd" DayOfWeekName
     , Tuple "ddd" DayOfWeekNameShort
+    , Tuple "d" DayOfWeek
     , Tuple "HH" Hours24
     , Tuple "hh" Hours12
     , Tuple "a" Meridiem
diff --git a/test/src/DateTime.purs b/test/src/DateTime.purs
index b938d34..ed5e490 100644
--- a/test/src/DateTime.purs
+++ b/test/src/DateTime.purs
@@ -24,7 +24,7 @@ datetimeTest = describe "Data.Formatter.DateTime" do
     , { format: "MMM D", dateStr: "Apr 1", date: makeDateTime 2017 4 1 0 0 0 0 }
     , { format: "dddd, MMM D", dateStr: "Saturday, Apr 1", date: makeDateTime 2017 4 1 0 0 0 0 }
     , { format: "ddd, MMM D", dateStr: "Sat, Apr 1", date: makeDateTime 2017 4 1 0 0 0 0 }
-    , { format: "E", dateStr: "6", date: makeDateTime 2017 4 1 0 0 0 0 }
+    , { format: "d", dateStr: "6", date: makeDateTime 2017 4 1 0 0 0 0 }
     , { format: "hh:mm:ss:SSS a", dateStr: "11:03:04:234 AM", date: makeDateTime 2017 4 12 11 3 4 234 }
     , { format: "YY", dateStr: "17", date: makeDateTime 2017 4 12 11 3 4 234 }
     , { format: "YY", dateStr: "17", date: makeDateTime 20017 4 12 0 0 0 0 } -- Format 20017 with YY
@@ -86,6 +86,13 @@ datetimeTest = describe "Data.Formatter.DateTime" do
       invalidDateformats
       (\f -> (FDT.parseFormatString f.str) `shouldEqual` (Left $ "Expected EOF " <> f.pos))
 
+  describe "parseFormatString/printFormatter should roundtrip" do
+    forAll
+      _.str
+      "should parse"
+      dateformats
+      (\f -> (FDT.printFormatter <$> FDT.parseFormatString f.str) `shouldEqual` (Right f.str))
+
   forAll
     (\a -> a.format <> " | " <> a.date)
     "s ≡ format (unformat s)"
@@ -200,7 +207,7 @@ dateformats =
         , FDT.MinutesTwoDigits
         ]
     }
-  , { str: "Y-MM-DD [at] HH:mm:ss:SSS"
+  , { str: "Y-MM-DD[ at ]HH:mm:ss:SSS"
     , lossless: true
     , format: fromFoldable
         [ FDT.YearAbsolute
@@ -230,4 +237,15 @@ dateformats =
         , FDT.Milliseconds
         ]
     }
+  , { str: "YYYY-DD-MM[X]"
+    , lossless: false
+    , format: fromFoldable
+        [ FDT.YearFull
+        , FDT.Placeholder "-"
+        , FDT.DayOfMonthTwoDigits
+        , FDT.Placeholder "-"
+        , FDT.MonthTwoDigits
+        , FDT.Placeholder "X"
+        ]
+    }
   ]