diff --git a/README.md b/README.md
index 6552bad..c5367c9 100644
--- a/README.md
+++ b/README.md
@@ -512,7 +512,7 @@ For example in `z.string().nullable()` will be rendered differently
   - `string` `type` mapping by default
 - ZodDefault
 - ZodDiscriminatedUnion
-  - `discriminator` mapping when all schemas in the union contain a `ref`.
+  - `discriminator` mapping when all schemas in the union are [registered](#creating-components). The discriminator must be a `ZodLiteral` string value. Only `ZodLiteral` values wrapped in `ZodBranded`, `ZodReadOnly` and `ZodCatch` are supported.
 - ZodEffects
   - `transform` support for request schemas. See [Zod Effects](#zod-effects) for how to enable response schema support
   - `pre-process` support. We assume that the input type is the same as the output type. Otherwise pipe and transform can be used instead.
diff --git a/src/create/schema/parsers/discriminatedUnion.test.ts b/src/create/schema/parsers/discriminatedUnion.test.ts
index 5201b31..b13d9bd 100644
--- a/src/create/schema/parsers/discriminatedUnion.test.ts
+++ b/src/create/schema/parsers/discriminatedUnion.test.ts
@@ -177,4 +177,185 @@ describe('createDiscriminatedUnionSchema', () => {
 
     expect(result).toEqual(expected);
   });
+
+  it('handles a discriminated union with an optional type', () => {
+    const expected: Schema = {
+      type: 'schema',
+      schema: {
+        oneOf: [
+          {
+            $ref: '#/components/schemas/a',
+          },
+          {
+            $ref: '#/components/schemas/b',
+          },
+        ],
+      },
+    };
+    const schema = z.discriminatedUnion('type', [
+      z
+        .object({
+          type: z.literal('a').optional(),
+        })
+        .openapi({ ref: 'a' }),
+      z
+        .object({
+          type: z.literal('b'),
+        })
+        .openapi({ ref: 'b' }),
+    ]);
+
+    const result = createDiscriminatedUnionSchema(schema, createOutputState());
+
+    expect(result).toEqual(expected);
+  });
+
+  it('handles a discriminated union with a nullable type', () => {
+    const expected: Schema = {
+      type: 'schema',
+      schema: {
+        oneOf: [
+          {
+            $ref: '#/components/schemas/a',
+          },
+          {
+            $ref: '#/components/schemas/b',
+          },
+        ],
+      },
+    };
+    const schema = z.discriminatedUnion('type', [
+      z
+        .object({
+          type: z.literal('a').nullable(),
+        })
+        .openapi({ ref: 'a' }),
+      z
+        .object({
+          type: z.literal('b'),
+        })
+        .openapi({ ref: 'b' }),
+    ]);
+
+    const result = createDiscriminatedUnionSchema(schema, createOutputState());
+
+    expect(result).toEqual(expected);
+  });
+
+  it('handles a discriminated union with a branded type', () => {
+    const expected: Schema = {
+      type: 'schema',
+      schema: {
+        discriminator: {
+          mapping: {
+            a: '#/components/schemas/a',
+            b: '#/components/schemas/b',
+          },
+          propertyName: 'type',
+        },
+        oneOf: [
+          {
+            $ref: '#/components/schemas/a',
+          },
+          {
+            $ref: '#/components/schemas/b',
+          },
+        ],
+      },
+    };
+    const schema = z.discriminatedUnion('type', [
+      z
+        .object({
+          type: z.literal('a').brand(),
+        })
+        .openapi({ ref: 'a' }),
+      z
+        .object({
+          type: z.literal('b'),
+        })
+        .openapi({ ref: 'b' }),
+    ]);
+
+    const result = createDiscriminatedUnionSchema(schema, createOutputState());
+
+    expect(result).toEqual(expected);
+  });
+
+  it('handles a discriminated union with a readonly type', () => {
+    const expected: Schema = {
+      type: 'schema',
+      schema: {
+        discriminator: {
+          mapping: {
+            a: '#/components/schemas/a',
+            b: '#/components/schemas/b',
+          },
+          propertyName: 'type',
+        },
+        oneOf: [
+          {
+            $ref: '#/components/schemas/a',
+          },
+          {
+            $ref: '#/components/schemas/b',
+          },
+        ],
+      },
+    };
+    const schema = z.discriminatedUnion('type', [
+      z
+        .object({
+          type: z.literal('a').readonly(),
+        })
+        .openapi({ ref: 'a' }),
+      z
+        .object({
+          type: z.literal('b'),
+        })
+        .openapi({ ref: 'b' }),
+    ]);
+
+    const result = createDiscriminatedUnionSchema(schema, createOutputState());
+
+    expect(result).toEqual(expected);
+  });
+
+  it('handles a discriminated union with a catch type', () => {
+    const expected: Schema = {
+      type: 'schema',
+      schema: {
+        discriminator: {
+          mapping: {
+            a: '#/components/schemas/a',
+            b: '#/components/schemas/b',
+          },
+          propertyName: 'type',
+        },
+        oneOf: [
+          {
+            $ref: '#/components/schemas/a',
+          },
+          {
+            $ref: '#/components/schemas/b',
+          },
+        ],
+      },
+    };
+    const schema = z.discriminatedUnion('type', [
+      z
+        .object({
+          type: z.literal('a').catch('a'),
+        })
+        .openapi({ ref: 'a' }),
+      z
+        .object({
+          type: z.literal('b'),
+        })
+        .openapi({ ref: 'b' }),
+    ]);
+
+    const result = createDiscriminatedUnionSchema(schema, createOutputState());
+
+    expect(result).toEqual(expected);
+  });
 });
diff --git a/src/create/schema/parsers/discriminatedUnion.ts b/src/create/schema/parsers/discriminatedUnion.ts
index 6a3f969..dee360f 100644
--- a/src/create/schema/parsers/discriminatedUnion.ts
+++ b/src/create/schema/parsers/discriminatedUnion.ts
@@ -2,8 +2,9 @@ import type {
   AnyZodObject,
   ZodDiscriminatedUnion,
   ZodDiscriminatedUnionOption,
-  ZodLiteralDef,
   ZodRawShape,
+  ZodType,
+  ZodTypeAny,
 } from 'zod';
 
 import type { oas31 } from '../../../openapi3-ts/dist';
@@ -32,7 +33,6 @@ export const createDiscriminatedUnionSchema = <
     schemaObjects,
     options,
     zodDiscriminatedUnion.discriminator,
-    state,
   );
   return {
     type: 'schema',
@@ -44,11 +44,35 @@ export const createDiscriminatedUnionSchema = <
   };
 };
 
+const unwrapLiteral = (
+  zodType: ZodType | ZodTypeAny | undefined,
+): string | undefined => {
+  if (isZodType(zodType, 'ZodLiteral')) {
+    if (typeof zodType._def.value !== 'string') {
+      return undefined;
+    }
+    return zodType._def.value;
+  }
+
+  if (isZodType(zodType, 'ZodBranded')) {
+    return unwrapLiteral(zodType._def.type);
+  }
+
+  if (isZodType(zodType, 'ZodReadonly')) {
+    return unwrapLiteral(zodType._def.innerType);
+  }
+
+  if (isZodType(zodType, 'ZodCatch')) {
+    return unwrapLiteral(zodType._def.innerType);
+  }
+
+  return undefined;
+};
+
 export const mapDiscriminator = (
   schemas: Array<oas31.SchemaObject | oas31.ReferenceObject>,
   zodObjects: AnyZodObject[],
   discriminator: unknown,
-  state: SchemaState,
 ): oas31.SchemaObject['discriminator'] => {
   if (typeof discriminator !== 'string') {
     return undefined;
@@ -71,14 +95,10 @@ export const mapDiscriminator = (
       continue;
     }
 
-    const literalValue = (value?._def as ZodLiteralDef<unknown>).value;
+    const literalValue = unwrapLiteral(value);
 
     if (typeof literalValue !== 'string') {
-      throw new Error(
-        `Discriminator ${discriminator} could not be found in on index ${index} of a discriminated union at ${state.path.join(
-          ' > ',
-        )}`,
-      );
+      return undefined;
     }
 
     mapping[literalValue] = componentSchemaRef;