diff --git a/.gitignore b/.gitignore
index 05b31c8..38d9e05 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,5 +14,7 @@ yarn.lock
 /node_modules/
 /output/
 /tmp/
+/.psc-package/
 
 .psc-ide-port
+
diff --git a/bower.json b/bower.json
index ba0167a..9fb0b06 100644
--- a/bower.json
+++ b/bower.json
@@ -20,17 +20,17 @@
     "url": "git://github.com/purescript-contrib/purescript-string-extras.git"
   },
   "dependencies": {
-    "purescript-strings": "^3.3.1",
-    "purescript-prelude": "^3.1.0",
-    "purescript-maybe": "^3.0.0",
-    "purescript-partial": "^1.2.1",
-    "purescript-either": "^3.1.0",
-    "purescript-foldable-traversable": "^3.6.1",
-    "purescript-unicode": "^3.0.1",
-    "purescript-arrays": "^4.2.0"
+    "purescript-strings": "^4.0.0",
+    "purescript-prelude": "^4.0.0",
+    "purescript-maybe": "^4.0.0",
+    "purescript-partial": "^2.0.0",
+    "purescript-either": "^4.0.0",
+    "purescript-foldable-traversable": "^4.0.0",
+    "purescript-unicode": "^4.0.0",
+    "purescript-arrays": "^5.0.0"
   },
   "devDependencies": {
-    "purescript-assert": "^3.0.0",
-    "purescript-console": "^3.0.0"
+    "purescript-assert": "^4.0.0",
+    "purescript-console": "^4.1.0"
   }
 }
diff --git a/package.json b/package.json
index 7daf55a..cfd3acf 100644
--- a/package.json
+++ b/package.json
@@ -6,9 +6,9 @@
     "test": "pulp test"
   },
   "devDependencies": {
-    "pulp": "^12.0.1",
-    "purescript": "^0.11.6",
-    "purescript-psa": "^0.5.1",
+    "pulp": "^12.3.0",
+    "purescript": "^0.12.0",
+    "purescript-psa": "^0.6.0",
     "rimraf": "^2.6.2"
   }
 }
diff --git a/psc-package.json b/psc-package.json
new file mode 100644
index 0000000..746e75d
--- /dev/null
+++ b/psc-package.json
@@ -0,0 +1,17 @@
+{
+  "name": "purescript-strings-extra",
+  "set": "psc-0.12.0",
+  "source": "https://github.com/purescript/package-sets.git",
+  "depends": [
+    "console",
+    "assert",
+    "arrays",
+    "unicode",
+    "foldable-traversable",
+    "either",
+    "partial",
+    "maybe",
+    "strings",
+    "prelude"
+  ]
+}
diff --git a/src/Data/String/Extra.purs b/src/Data/String/Extra.purs
index 01ad36f..e2895de 100644
--- a/src/Data/String/Extra.purs
+++ b/src/Data/String/Extra.purs
@@ -7,10 +7,12 @@ module Data.String.Extra
   ) where
 
 import Data.Array as Array
+import Data.Array.NonEmpty as NonEmptyArray
 import Data.Char.Unicode as Unicode
 import Data.Either (fromRight)
 import Data.Foldable (foldMap)
 import Data.String as String
+import Data.String.CodeUnits as SCU
 import Data.String.Regex (Regex)
 import Data.String.Regex as Regex
 import Data.String.Regex.Flags as Flags
@@ -66,8 +68,8 @@ words string =
 
 upfirst :: String -> String
 upfirst =
-  String.uncons >>> foldMap \{ head, tail } ->
-    String.singleton (Unicode.toUpper head) <> toUnicodeLower tail
+  SCU.uncons >>> foldMap \{ head, tail } ->
+    SCU.singleton (Unicode.toUpper head) <> toUnicodeLower tail
 
 regexGlobal :: String -> Regex
 regexGlobal regexStr =
@@ -76,7 +78,7 @@ regexGlobal regexStr =
 asciiWords :: String -> Array String
 asciiWords =
   Regex.match (regexGlobal "[^\x00-\x2f\x3a-\x40\x5b-\x60\x7b-\x7f]+")
-    >>> foldMap Array.catMaybes
+    >>> foldMap NonEmptyArray.catMaybes
 
 hasUnicodeWords :: String -> Boolean
 hasUnicodeWords =
@@ -84,15 +86,15 @@ hasUnicodeWords =
 
 toUnicodeLower :: String -> String
 toUnicodeLower =
-  String.toCharArray >>> map Unicode.toLower >>> String.fromCharArray
+  SCU.toCharArray >>> map Unicode.toLower >>> SCU.fromCharArray
 
 toUnicodeUpper :: String -> String
 toUnicodeUpper =
-  String.toCharArray >>> map Unicode.toUpper >>> String.fromCharArray
+  SCU.toCharArray >>> map Unicode.toUpper >>> SCU.fromCharArray
 
 unicodeWords :: String -> Array String
 unicodeWords =
-  Regex.match (regexGlobal regexStr) >>> foldMap Array.catMaybes
+  Regex.match (regexGlobal regexStr) >>> foldMap NonEmptyArray.catMaybes
   where
     -- https://github.com/lodash/lodash/blob/master/.internal/unicodeWords.js
     -- Used to compose unicode character classes.
diff --git a/test/Main.purs b/test/Main.purs
index c8e964f..f4e3ff6 100644
--- a/test/Main.purs
+++ b/test/Main.purs
@@ -1,12 +1,12 @@
 module Test.Main where
 
-import Control.Monad.Eff (Eff)
-import Control.Monad.Eff.Console (CONSOLE, log)
 import Data.String.Extra as String
+import Effect (Effect)
+import Effect.Console (log)
 import Prelude (Unit, ($), (==), (*>), discard)
-import Test.Assert (ASSERT, assert)
+import Test.Assert (assert)
 
-main :: forall eff. Eff (assert :: ASSERT, console :: CONSOLE | eff) Unit
+main :: Effect Unit
 main = do
   log "camelCase" *> do
     assert $ String.camelCase "" == ""