diff --git a/.prettierignore b/.prettierignore
index 745b019..ed95976 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -2,3 +2,4 @@
 /.makefiles/
 /artifacts/
 /CHANGELOG.md
+/test/fixture/specification/no-prettier/
diff --git a/src/specification.ts b/src/specification.ts
index 4da7d6f..cd1db27 100644
--- a/src/specification.ts
+++ b/src/specification.ts
@@ -37,9 +37,13 @@ export async function render(variables: Variable<unknown>[]): Promise<string> {
 async function prettyPrint(markdown: string): Promise<string> {
   try {
     const prettier = await import("prettier");
-    const options =
-      (await prettier.resolveConfig(join(process.cwd(), "ENVIRONMENT.md"))) ??
-      {};
+
+    const options = (await prettier.resolveConfig(
+      join(process.cwd(), "ENVIRONMENT.md"),
+    )) ?? {
+      printWidth: 80,
+      proseWrap: "always",
+    };
 
     return (
       await prettier.format(markdown, { ...options, parser: "markdown" })
diff --git a/test/fixture/specification/no-prettier/prettier-not-configured.md b/test/fixture/specification/no-prettier/prettier-not-configured.md
new file mode 100644
index 0000000..eb78f5d
--- /dev/null
+++ b/test/fixture/specification/no-prettier/prettier-not-configured.md
@@ -0,0 +1,35 @@
+# Environment variables
+
+The `<app>` app uses **declarative environment variables** powered by
+**[Austenite]**.
+
+[austenite]: https://github.com/ezzatron/austenite
+
+| Name            | Usage    | Description     |
+| :-------------- | :------- | :-------------- |
+| [`LOGO`](#logo) | Required | Main logo image |
+
+<!-- prettier-ignore-start -->
+
+> [!TIP]
+> If you set an empty value for an environment variable, the app behaves as if that variable isn't set.
+
+<!-- prettier-ignore-end -->
+
+## `LOGO`
+
+_Main logo image_
+
+The `LOGO` variable is a **required** variable that takes **absolute URL**
+values, or **relative URL** values relative to
+`https://base.example.org/path/to/resource`.
+
+### Example values
+
+```sh
+export LOGO=https://host.example.org/path/to/resource # URL (absolute)
+```
+
+```sh
+export LOGO=path/to/resource # URL (relative)
+```
diff --git a/test/fixture/specification/no-prettier/prettier-unavailable.md b/test/fixture/specification/no-prettier/prettier-unavailable.md
new file mode 100644
index 0000000..77c4a1c
--- /dev/null
+++ b/test/fixture/specification/no-prettier/prettier-unavailable.md
@@ -0,0 +1,32 @@
+# Environment variables
+
+The `<app>` app uses **declarative environment variables** powered by **[Austenite]**.
+
+[austenite]: https://github.com/ezzatron/austenite
+
+| Name            | Usage    | Description     |
+| :-------------- | :------- | :-------------- |
+| [`LOGO`](#logo) | Required | Main logo image |
+
+<!-- prettier-ignore-start -->
+
+> [!TIP]
+> If you set an empty value for an environment variable, the app behaves as if that variable isn't set.
+
+<!-- prettier-ignore-end -->
+
+## `LOGO`
+
+_Main logo image_
+
+The `LOGO` variable is a **required** variable that takes **absolute URL** values, or **relative URL** values relative to `https://base.example.org/path/to/resource`.
+
+### Example values
+
+```sh
+export LOGO=https://host.example.org/path/to/resource # URL (absolute)
+```
+
+```sh
+export LOGO=path/to/resource # URL (relative)
+```
diff --git a/test/suite/specification-prettier.spec.ts b/test/suite/specification-prettier.spec.ts
new file mode 100644
index 0000000..bda6fd4
--- /dev/null
+++ b/test/suite/specification-prettier.spec.ts
@@ -0,0 +1,100 @@
+import { join } from "path";
+import { fileURLToPath } from "url";
+import {
+  afterAll,
+  beforeAll,
+  beforeEach,
+  describe,
+  expect,
+  it,
+  vi,
+} from "vitest";
+import { initialize, url } from "../../src/index.js";
+import { MockConsole, createMockConsole } from "../helpers.js";
+
+const fixturesPath = fileURLToPath(
+  new URL("../fixture/specification", import.meta.url),
+);
+
+describe("Specification documents (Prettier unavailable)", () => {
+  let exitCode: number | undefined;
+  let mockConsole: MockConsole;
+
+  beforeEach(() => {
+    exitCode = undefined;
+    vi.spyOn(process, "exit").mockImplementation((code) => {
+      exitCode = code ?? 0;
+
+      return undefined as never;
+    });
+
+    process.env = {
+      AUSTENITE_SPEC: "true",
+    };
+
+    mockConsole = createMockConsole();
+  });
+
+  describe("when Prettier is not installed", () => {
+    beforeAll(() => {
+      // eslint-disable-next-line @typescript-eslint/require-await
+      vi.doMock("prettier", async () => {
+        throw new Error('Cannot find module "prettier"');
+      });
+    });
+
+    afterAll(() => {
+      vi.doUnmock("prettier");
+    });
+
+    it("doesn't pretty print the specification output", async () => {
+      url("LOGO", "Main logo image", {
+        base: new URL("https://base.example.org/path/to/resource"),
+      });
+      await initialize();
+
+      await expect(mockConsole.readStdout()).toMatchFileSnapshot(
+        fixturePath("no-prettier/prettier-unavailable"),
+      );
+      expect(exitCode).toBe(0);
+    });
+  });
+
+  describe("when Prettier is installed but not configured", () => {
+    beforeAll(() => {
+      // eslint-disable-next-line @typescript-eslint/require-await
+      vi.doMock("prettier", async () => {
+        const prettier = await vi.importActual("prettier");
+
+        return {
+          ...prettier,
+
+          // eslint-disable-next-line @typescript-eslint/require-await
+          async resolveConfig() {
+            return null;
+          },
+        };
+      });
+    });
+
+    afterAll(() => {
+      vi.doUnmock("prettier");
+    });
+
+    it("uses prose wrap at 80 columns", async () => {
+      url("LOGO", "Main logo image", {
+        base: new URL("https://base.example.org/path/to/resource"),
+      });
+      await initialize();
+
+      await expect(mockConsole.readStdout()).toMatchFileSnapshot(
+        fixturePath("no-prettier/prettier-not-configured"),
+      );
+      expect(exitCode).toBe(0);
+    });
+  });
+});
+
+function fixturePath(name: string): string {
+  return join(fixturesPath, `${name}.md`);
+}