diff --git a/plugin/data.ts b/plugin/data.ts
index 5a85235..fd7924a 100644
--- a/plugin/data.ts
+++ b/plugin/data.ts
@@ -1,4 +1,4 @@
-import { GetModuleInfo } from "rollup";
+import type { GetModuleInfo } from "./rollup-types.js";
 import { isModuleTree, ModuleLengths, ModuleTree, ModuleTreeLeaf } from "../shared/types.js";
 import { ModuleMapper } from "./module-mapper.js";
 
diff --git a/plugin/index.ts b/plugin/index.ts
index 689109e..ae477e1 100644
--- a/plugin/index.ts
+++ b/plugin/index.ts
@@ -1,7 +1,8 @@
 import { promises as fs } from "node:fs";
 import path from "node:path";
 
-import { OutputBundle, Plugin, NormalizedOutputOptions, OutputOptions } from "rollup";
+import type { OutputBundle, NormalizedOutputOptions } from "rollup";
+import type { Plugin, OutputOptions } from "./rollup-types.js";
 import opn, { Options as OpenOptions } from "open";
 
 import { ModuleLengths, ModuleTree, ModuleTreeLeaf, VisualizerData } from "../shared/types.js";
@@ -140,7 +141,7 @@ export const visualizer = (
       outputOptions: NormalizedOutputOptions,
       outputBundle: OutputBundle,
     ): Promise<void> {
-      opts = typeof opts === "function" ? opts(outputOptions) : opts;
+      opts = typeof opts === "function" ? opts(outputOptions as unknown as OutputOptions) : opts;
 
       if ("json" in opts) {
         this.warn(WARN_JSON_DEPRECATED);
diff --git a/plugin/rollup-types.ts b/plugin/rollup-types.ts
new file mode 100644
index 0000000..7af8e12
--- /dev/null
+++ b/plugin/rollup-types.ts
@@ -0,0 +1,44 @@
+// Structural stubs for rollup/rolldown types. Both bundlers are optional peer
+// deps, so the published .d.ts files can't hard-import from either.
+
+export interface OutputOptions {
+  dir?: string;
+  file?: string;
+  format?: string;
+  name?: string;
+  entryFileNames?: string | ((chunkInfo: any) => string);
+  chunkFileNames?: string | ((chunkInfo: any) => string);
+  assetFileNames?: string | ((assetInfo: any) => string);
+  sourcemap?: boolean | "inline" | "hidden";
+  banner?: unknown;
+  footer?: unknown;
+  intro?: unknown;
+  outro?: unknown;
+  globals?: unknown;
+  exports?: "auto" | "default" | "named" | "none";
+}
+
+export interface Plugin {
+  name: string;
+  generateBundle?: (
+    this: any,
+    options: any,
+    bundle: any,
+    isWrite?: boolean,
+  ) => void | Promise<void>;
+}
+
+export interface OutputChunk {
+  type: "chunk";
+  code: string;
+  map?: unknown;
+  facadeModuleId?: string | null;
+  modules: Record<string, { renderedLength: number; code: string | null }>;
+}
+
+export type GetModuleInfo = (moduleId: string) => {
+  isEntry: boolean;
+  isExternal: boolean;
+  importedIds: readonly string[];
+  dynamicallyImportedIds?: readonly string[];
+} | null;
diff --git a/plugin/sourcemap.ts b/plugin/sourcemap.ts
index 6ed061e..4889101 100644
--- a/plugin/sourcemap.ts
+++ b/plugin/sourcemap.ts
@@ -1,5 +1,5 @@
 import path from "node:path";
-import { OutputChunk } from "rollup";
+import type { OutputChunk } from "./rollup-types.js";
 import type { RawSourceMap } from "source-map";
 import { SourceMapConsumer } from "source-map";