diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3128f8e..014e038 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@ Breaking changes:
 New features:
 
 Bugfixes:
+ - `URLSearchParams.keys` and `.values` returned undefined due to a bug in the foreign code (#22 by @cakekindel)
 
 Other improvements:
 - Rename `uneffectfulHref` to `hrefPure` (used in `Show` instance) (#21 by @JordanMartinez)
diff --git a/bower.json b/bower.json
index 4470a66..197975b 100644
--- a/bower.json
+++ b/bower.json
@@ -19,6 +19,7 @@
     "purescript-tuples": "^7.0.0"
   },
   "devDependencies": {
-    "purescript-assert": "^6.0.0"
+    "purescript-assert": "^6.0.0",
+    "purescript-ordered-collections": "^3.1.1"
   }
 }
diff --git a/package.json b/package.json
index 4ed063e..6c93cdb 100644
--- a/package.json
+++ b/package.json
@@ -3,12 +3,14 @@
   "scripts": {
     "clean": "rimraf output && rimraf .pulp-cache",
     "build": "eslint src && pulp build -- --censor-lib --strict",
-    "test": "pulp test -- --censor-lib --strict"
+    "test": "pulp test -- --censor-lib --strict",
+    "fmt": "purs-tidy format-in-place 'src/**/*.purs' 'test/**/*.purs'"
   },
   "devDependencies": {
     "eslint": "^7.15.0",
     "pulp": "16.0.0-0",
     "purescript-psa": "^0.8.2",
+    "purs-tidy": "^0.10.0",
     "rimraf": "^3.0.2"
   }
 }
diff --git a/src/Node/URL/URLSearchParams.js b/src/Node/URL/URLSearchParams.js
index 3c185cd..55aa984 100644
--- a/src/Node/URL/URLSearchParams.js
+++ b/src/Node/URL/URLSearchParams.js
@@ -21,8 +21,8 @@ export const entriesImpl = (params, tuple) => {
   return arr;
 };
 export const keysImpl = (params) => {
-  Array.from(params.keys());
+  return Array.from(params.keys());
 };
 export const valuesImpl = (params) => {
-  Array.from(params.values());
+  return Array.from(params.values());
 };
diff --git a/test/Main.purs b/test/Main.purs
index dd259bb..f66190f 100644
--- a/test/Main.purs
+++ b/test/Main.purs
@@ -4,11 +4,53 @@ import Prelude
 
 import Effect (Effect)
 import Node.URL as URL
+import Node.URL.URLSearchParams as URL.Search
+import Foreign (unsafeReadTagged)
+import Data.Bifunctor (lmap)
+import Control.Monad.Except (runExcept)
+import Control.Monad.Error.Class (liftEither)
+import Effect.Exception (error)
+import Data.Traversable (for)
+import Data.Tuple (Tuple(..))
+import Data.Map as Map
 import Test.Assert (assertEqual)
 
 main ∷ Effect Unit
 main = do
-  let urlStr = "http://example.com/"
-  url <- URL.new urlStr
-  urlStr' <- URL.format url
-  assertEqual { expected: urlStr, actual: urlStr' }
+  -- Simple roundtrip
+  do
+    let urlStr = "http://example.com/"
+    url <- URL.new urlStr
+    urlStr' <- URL.format url
+    assertEqual { expected: urlStr, actual: urlStr' }
+
+  -- URLSearchParams
+  do
+    let urlStr = "http://example.com/?k&v=a&k&v=b"
+    url <- URL.new urlStr
+    search <- URL.searchParams url
+    keys <- URL.Search.keys search
+    valuesForeign <- URL.Search.values search
+
+    let
+      getStringOrThrow =
+        liftEither
+          <<< lmap (error <<< show)
+          <<< runExcept
+          <<< unsafeReadTagged "String"
+
+    values <- for valuesForeign getStringOrThrow
+
+    map <- Map.fromFoldable <$> for keys \k -> do
+      vs <- URL.Search.getAll k search
+      pure $ Tuple k vs
+
+    assertEqual { actual: keys, expected: [ "k", "v", "k", "v" ] }
+    assertEqual { actual: values, expected: [ "", "a", "", "b" ] }
+    assertEqual
+      { actual: map
+      , expected: Map.fromFoldable
+          [ Tuple "k" [ "", "" ]
+          , Tuple "v" [ "a", "b" ]
+          ]
+      }