diff --git a/src/util/parameterize.ts b/src/util/parameterize.ts
index f0c6cf1..2988e45 100644
--- a/src/util/parameterize.ts
+++ b/src/util/parameterize.ts
@@ -34,15 +34,9 @@ const parameterize = (obj: any, prefix?: string): string => {
   return str.join("&")
 }
 
-// IE does not encode by default like other browsers
 const maybeEncode = (value: string): string => {
-  var isBrowser =
-    typeof window !== "undefined" &&
-    typeof window.navigator.userAgent !== "undefined"
-  const isIE = isBrowser && window.navigator.userAgent.match(/(MSIE|Trident)/)
-  const isEncoded = typeof value === "string" && value.indexOf("%") !== -1
-  const shouldEncode = isBrowser && isIE && !isEncoded
-  return shouldEncode ? encodeURIComponent(value) : value
+  var isEncoded = typeof value === "string" && decodeURI(value) !== value
+  return isEncoded ? value : encodeURIComponent(value)
 }
 
 export { parameterize as default }
diff --git a/test/integration/finders.test.ts b/test/integration/finders.test.ts
index 7ea5891..4c7eb7b 100644
--- a/test/integration/finders.test.ts
+++ b/test/integration/finders.test.ts
@@ -574,7 +574,7 @@ describe("Model finders", () => {
 
   describe("#includes", () => {
     beforeEach(() => {
-      fetchMock.get("http://example.com/api/v1/people?include=a.b,a.c.d", {
+      fetchMock.get("http://example.com/api/v1/people?include=a.b%2Ca.c.d", {
         data: [
           {
             id: "2",
diff --git a/test/integration/relations.test.ts b/test/integration/relations.test.ts
index 1d5cace..bf3e272 100644
--- a/test/integration/relations.test.ts
+++ b/test/integration/relations.test.ts
@@ -59,7 +59,7 @@ describe("Relations", () => {
   describe("#find()", () => {
     beforeEach(() => {
       fetchMock.get(
-        "http://example.com/api/v1/authors/1?include=books,multi_words",
+        "http://example.com/api/v1/authors/1?include=books%2Cmulti_words",
         generateMockResponse("authors")
       )
     })
@@ -103,7 +103,7 @@ describe("Relations", () => {
   describe("when keyCase is snake_case", () => {
     beforeEach(() => {
       fetchMock.get(
-        "http://example.com/api/v1/non_fiction_authors/1?include=books,multi_words",
+        "http://example.com/api/v1/non_fiction_authors/1?include=books%2Cmulti_words",
         generateMockResponse("non_fiction_authors")
       )
     })
diff --git a/test/unit/scope.test.ts b/test/unit/scope.test.ts
index c5dc5a8..f93b331 100644
--- a/test/unit/scope.test.ts
+++ b/test/unit/scope.test.ts
@@ -342,7 +342,17 @@ describe("Scope", () => {
         .stats({ total: "count" })
         .includes({ a: ["b", { c: "d" }] })
       expect(scope.toQueryParams()).to.eq(
-        "page[number]=2&page[size]=10&filter[foo_bar]=baz&sort=foo,-bar&fields[people]=name,age&stats[total]=count&include=a.b,a.c.d"
+        "page[number]=2&page[size]=10&filter[foo_bar]=baz&sort=foo,-bar&fields[people]=name,age&stats[total]=count&include=a.b%2Ca.c.d"
+      )
+    })
+
+    it("correctly encodes special characters", () => {
+      scope = scope.where({
+        octothorp: "one # two",
+        ampersand: "three & four"
+      })
+      expect(scope.toQueryParams()).to.eq(
+        "filter[octothorp]=one%20%23%20two&filter[ampersand]=three%20%26%20four"
       )
     })
 
@@ -366,7 +376,7 @@ describe("Scope", () => {
       })
 
       it("casts arrays correctly", () => {
-        scope = scope.extraParams({ foo: "bar,baz" })
+        scope = scope.extraParams({ foo: ["bar", "baz"] })
         expect(<string>scope.toQueryParams()).to.eq("foo=bar,baz")
       })