diff --git a/README.md b/README.md
index 6c7991a..bc87c0c 100644
--- a/README.md
+++ b/README.md
@@ -29,7 +29,7 @@ import { pascalCase } from "scule";
 
 ## Utils
 
-### `pascalCase(str)`
+### `pascalCase(str, opts?: { normalize })`
 
 Splits string and joins by PascalCase convention:
 
@@ -38,9 +38,9 @@ pascalCase("foo-bar_baz");
 // FooBarBaz
 ```
 
-**Notice:** If an uppercase letter is followed by other uppercase letters (like `FooBAR`), they are preserved.
+**Notice:** If an uppercase letter is followed by other uppercase letters (like `FooBAR`), they are preserved. You can use `{ normalize: true }` for strictly following pascalCase convention.
 
-### `camelCase`
+### `camelCase(str, opts?: { normalize })`
 
 Splits string and joins by camelCase convention:
 
diff --git a/src/index.ts b/src/index.ts
index cd5d9f1..afd7485 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -4,6 +4,7 @@ import type {
   PascalCase,
   SnakeCase,
   SplitByCase,
+  CaseOptions,
 } from "./types";
 
 const NUMBER_CHAR_RE = /\d/;
@@ -86,23 +87,34 @@ export function lowerFirst<S extends string>(str: S): Uncapitalize<S> {
 }
 
 export function pascalCase(): "";
-export function pascalCase<T extends string | readonly string[]>(
-  str: T,
-): PascalCase<T>;
-export function pascalCase<T extends string | readonly string[]>(str?: T) {
+export function pascalCase<
+  T extends string | readonly string[],
+  UserCaseOptions extends CaseOptions = CaseOptions,
+>(str: T, opts?: CaseOptions): PascalCase<T, UserCaseOptions["normalize"]>;
+export function pascalCase<
+  T extends string | readonly string[],
+  UserCaseOptions extends CaseOptions = CaseOptions,
+>(str?: T, opts?: UserCaseOptions) {
   return str
     ? ((Array.isArray(str) ? str : splitByCase(str as string))
-        .map((p) => upperFirst(p.toLowerCase()))
-        .join("") as PascalCase<T>)
+        .map((p) => upperFirst(opts?.normalize ? p.toLowerCase() : p))
+        .join("") as PascalCase<T, UserCaseOptions["normalize"]>)
     : "";
 }
 
 export function camelCase(): "";
-export function camelCase<T extends string | readonly string[]>(
-  str: T,
-): CamelCase<T>;
-export function camelCase<T extends string | readonly string[]>(str?: T) {
-  return lowerFirst(pascalCase(str || "")) as CamelCase<T>;
+export function camelCase<
+  T extends string | readonly string[],
+  UserCaseOptions extends CaseOptions = CaseOptions,
+>(str: T, opts?: UserCaseOptions): CamelCase<T, UserCaseOptions["normalize"]>;
+export function camelCase<
+  T extends string | readonly string[],
+  UserCaseOptions extends CaseOptions = CaseOptions,
+>(str?: T, opts?: UserCaseOptions) {
+  return lowerFirst(pascalCase(str || "", opts)) as CamelCase<
+    T,
+    UserCaseOptions["normalize"]
+  >;
 }
 
 export function kebabCase(): "";
diff --git a/src/types.ts b/src/types.ts
index 573e874..d1e72e8 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -18,8 +18,13 @@ type SameLetterCase<
 type CapitalizedWords<
   T extends readonly string[],
   Accumulator extends string = "",
+  Normalize extends boolean | undefined = false,
 > = T extends readonly [infer F extends string, ...infer R extends string[]]
-  ? CapitalizedWords<R, `${Accumulator}${Capitalize<Lowercase<F>>}`>
+  ? CapitalizedWords<
+      R,
+      `${Accumulator}${Capitalize<Normalize extends true ? Lowercase<F> : F>}`,
+      Normalize
+    >
   : Accumulator;
 type JoinLowercaseWords<
   T extends readonly string[],
@@ -36,6 +41,10 @@ type RemoveLastOfArray<T extends any[]> = T extends [...infer F, any]
   ? F
   : never;
 
+export type CaseOptions = {
+  normalize?: boolean;
+};
+
 export type SplitByCase<
   T,
   Separator extends string = Splitter,
@@ -104,23 +113,29 @@ export type JoinByCase<T, Joiner extends string> = string extends T
         ? JoinLowercaseWords<T, Joiner>
         : never;
 
-export type PascalCase<T> = string extends T
+export type PascalCase<
+  T,
+  Normalize extends boolean | undefined = false,
+> = string extends T
   ? string
   : string[] extends T
     ? string
     : T extends string
       ? SplitByCase<T> extends readonly string[]
-        ? CapitalizedWords<SplitByCase<T>>
+        ? CapitalizedWords<SplitByCase<T>, "", Normalize>
         : never
       : T extends readonly string[]
-        ? CapitalizedWords<T>
+        ? CapitalizedWords<T, "", Normalize>
         : never;
 
-export type CamelCase<T> = string extends T
+export type CamelCase<
+  T,
+  Normalize extends boolean | undefined = false,
+> = string extends T
   ? string
   : string[] extends T
     ? string
-    : Uncapitalize<PascalCase<T>>;
+    : Uncapitalize<PascalCase<T, Normalize>>;
 
 export type KebabCase<
   T extends string | readonly string[],
diff --git a/test/scule.test.ts b/test/scule.test.ts
index cb17472..08fa309 100644
--- a/test/scule.test.ts
+++ b/test/scule.test.ts
@@ -47,7 +47,7 @@ describe("pascalCase", () => {
     ["FOO_BAR", "FooBar"],
     ["foo--bar-Baz", "FooBarBaz"],
   ])("%s => %s", (input, expected) => {
-    expect(pascalCase(input)).toMatchObject(expected);
+    expect(pascalCase(input, { normalize: true })).toMatchObject(expected);
   });
 });
 
@@ -56,7 +56,7 @@ describe("camelCase", () => {
     ["FooBarBaz", "fooBarBaz"],
     ["FOO_BAR", "fooBar"],
   ])("%s => %s", (input, expected) => {
-    expect(camelCase(input)).toMatchObject(expected);
+    expect(camelCase(input, { normalize: true })).toMatchObject(expected);
   });
 });
 
diff --git a/test/types.test-d.ts b/test/types.test-d.ts
index 17267e7..4a9a4a8 100644
--- a/test/types.test-d.ts
+++ b/test/types.test-d.ts
@@ -37,23 +37,23 @@ describe("SplitByCase", () => {
 
 describe("PascalCase", () => {
   test("types", () => {
-    expectTypeOf<PascalCase<string>>().toEqualTypeOf<string>();
-    expectTypeOf<PascalCase<string[]>>().toEqualTypeOf<string>();
+    expectTypeOf<PascalCase<string, true>>().toEqualTypeOf<string>();
+    expectTypeOf<PascalCase<string[], true>>().toEqualTypeOf<string>();
   });
 
   test("string", () => {
-    assertType<PascalCase<"">>("");
-    assertType<PascalCase<"foo">>("Foo");
-    assertType<PascalCase<"foo-bAr">>("FooBAr");
-    assertType<PascalCase<"FooBARb">>("FooBaRb");
-    assertType<PascalCase<"foo_bar-baz/qux">>("FooBarBazQux");
-    assertType<PascalCase<"foo--bar-Baz">>("FooBarBaz");
-    assertType<PascalCase<"FOO_BAR">>("FooBar");
+    assertType<PascalCase<"", true>>("");
+    assertType<PascalCase<"foo", true>>("Foo");
+    assertType<PascalCase<"foo-bAr", true>>("FooBAr");
+    assertType<PascalCase<"FooBARb", true>>("FooBaRb");
+    assertType<PascalCase<"foo_bar-baz/qux", true>>("FooBarBazQux");
+    assertType<PascalCase<"foo--bar-Baz", true>>("FooBarBaz");
+    assertType<PascalCase<"FOO_BAR", true>>("FooBar");
   });
 
   test("array", () => {
-    assertType<PascalCase<["foo", "Bar"]>>("FooBar");
-    assertType<PascalCase<["foo", "Bar", "fuzz", "FI", "Zz"]>>(
+    assertType<PascalCase<["foo", "Bar"], true>>("FooBar");
+    assertType<PascalCase<["foo", "Bar", "fuzz", "FI", "Zz"], true>>(
       "FooBarFuzzFiZz",
     );
   });
@@ -61,20 +61,20 @@ describe("PascalCase", () => {
 
 describe("CamelCase", () => {
   test("types", () => {
-    expectTypeOf<CamelCase<string>>().toEqualTypeOf<string>();
-    expectTypeOf<CamelCase<string[]>>().toEqualTypeOf<string>();
+    expectTypeOf<CamelCase<string, true>>().toEqualTypeOf<string>();
+    expectTypeOf<CamelCase<string[], true>>().toEqualTypeOf<string>();
   });
 
   test("string", () => {
-    assertType<CamelCase<"">>("");
-    assertType<CamelCase<"foo">>("foo");
-    assertType<CamelCase<"FooBARb">>("fooBaRb");
-    assertType<CamelCase<"foo_bar-baz/qux">>("fooBarBazQux");
-    assertType<CamelCase<"FOO_BAR">>("fooBar");
+    assertType<CamelCase<"", true>>("");
+    assertType<CamelCase<"foo", true>>("foo");
+    assertType<CamelCase<"FooBARb", true>>("fooBaRb");
+    assertType<CamelCase<"foo_bar-baz/qux", true>>("fooBarBazQux");
+    assertType<CamelCase<"FOO_BAR", true>>("fooBar");
   });
 
   test("array", () => {
-    assertType<CamelCase<["Foo", "Bar"]>>("fooBar");
+    assertType<CamelCase<["Foo", "Bar"], true>>("fooBar");
   });
 });