diff --git a/src/utils/__fixtures__/Fetcher/https:api.themoviedb.org3movie931944external_ids b/src/utils/__fixtures__/Fetcher/https:api.themoviedb.org3movie931944external_ids
new file mode 100644
index 0000000..bf11338
--- /dev/null
+++ b/src/utils/__fixtures__/Fetcher/https:api.themoviedb.org3movie931944external_ids
@@ -0,0 +1 @@
+{"id":931944,"imdb_id":"tt29141112","wikidata_id":"Q123992189","facebook_id":null,"instagram_id":null,"twitter_id":null}
\ No newline at end of file
diff --git a/src/utils/__fixtures__/Fetcher/https:api.themoviedb.org3tv12345678external_ids.error b/src/utils/__fixtures__/Fetcher/https:api.themoviedb.org3tv12345678external_ids.error
new file mode 100644
index 0000000..c31051e
--- /dev/null
+++ b/src/utils/__fixtures__/Fetcher/https:api.themoviedb.org3tv12345678external_ids.error
@@ -0,0 +1 @@
+Fetcher error: 404: Not Found
\ No newline at end of file
diff --git a/src/utils/__fixtures__/Fetcher/https:api.themoviedb.org3tv42009external_ids b/src/utils/__fixtures__/Fetcher/https:api.themoviedb.org3tv42009external_ids
new file mode 100644
index 0000000..3daddc4
--- /dev/null
+++ b/src/utils/__fixtures__/Fetcher/https:api.themoviedb.org3tv42009external_ids
@@ -0,0 +1 @@
+{"id":42009,"imdb_id":"tt2085059","freebase_mid":"/m/0hhs506","freebase_id":null,"tvdb_id":253463,"tvrage_id":30348,"wikidata_id":"Q558112","facebook_id":"BlackMirrorNetflix","instagram_id":"","twitter_id":"blackmirror"}
\ No newline at end of file
diff --git a/src/utils/tmdb.test.ts b/src/utils/tmdb.test.ts
index d9746ad..76ee9b2 100644
--- a/src/utils/tmdb.test.ts
+++ b/src/utils/tmdb.test.ts
@@ -1,4 +1,4 @@
-import { getTmdbIdFromImdbId } from './tmdb';
+import { getImdbIdFromTmdbId, getTmdbIdFromImdbId } from './tmdb';
 import { Fetcher } from './Fetcher';
 import { Context } from '../types';
 jest.mock('../utils/Fetcher');
@@ -9,26 +9,40 @@ const ctx: Context = { id: 'id', ip: '127.0.0.1', config: { de: 'on' } };
 
 describe('getTmdbIdFromImdbId', () => {
   test('series', async () => {
-    const tmdbId = await getTmdbIdFromImdbId(ctx, fetcher, { id: 'tt2085059', series: 2, episode: 4 });
-
-    expect(tmdbId).toStrictEqual({
-      id: 42009,
-      series: 2,
-      episode: 4,
-    });
+    expect(await getTmdbIdFromImdbId(ctx, fetcher, { id: 'tt2085059', series: 2, episode: 4 }))
+      .toStrictEqual({ id: 42009, series: 2, episode: 4 });
+    expect(await getTmdbIdFromImdbId(ctx, fetcher, { id: 'tt2085059', series: 2, episode: 4 }))
+      .toStrictEqual({ id: 42009, series: 2, episode: 4 }); // from cache
   });
 
   test('movie', async () => {
-    const tmdbId = await getTmdbIdFromImdbId(ctx, fetcher, { id: 'tt29141112', series: undefined, episode: undefined });
-
-    expect(tmdbId).toStrictEqual({
-      id: 931944,
-      series: undefined,
-      episode: undefined,
-    });
+    expect(await getTmdbIdFromImdbId(ctx, fetcher, { id: 'tt29141112', series: undefined, episode: undefined }))
+      .toStrictEqual({ id: 931944, series: undefined, episode: undefined });
+    expect(await getTmdbIdFromImdbId(ctx, fetcher, { id: 'tt29141112', series: undefined, episode: undefined }))
+      .toStrictEqual({ id: 931944, series: undefined, episode: undefined }); // from cache
   });
 
   test('throws with invalid imdb id', async () => {
     await expect(getTmdbIdFromImdbId(ctx, fetcher, { id: 'tt12345678', series: 1, episode: 1 })).rejects.toThrow('Could not get TMDB ID of IMDb ID "tt12345678"');
   });
 });
+
+describe('getImdbIdFromTmdbId', () => {
+  test('series', async () => {
+    expect(await getImdbIdFromTmdbId(ctx, fetcher, { id: 42009, series: 2, episode: 4 }))
+      .toStrictEqual({ id: 'tt2085059', series: 2, episode: 4 });
+    expect(await getImdbIdFromTmdbId(ctx, fetcher, { id: 42009, series: 2, episode: 4 }))
+      .toStrictEqual({ id: 'tt2085059', series: 2, episode: 4 }); // from cache
+  });
+
+  test('movie', async () => {
+    expect(await getImdbIdFromTmdbId(ctx, fetcher, { id: 931944, series: undefined, episode: undefined }))
+      .toStrictEqual({ id: 'tt29141112', series: undefined, episode: undefined });
+    expect(await getImdbIdFromTmdbId(ctx, fetcher, { id: 931944, series: undefined, episode: undefined }))
+      .toStrictEqual({ id: 'tt29141112', series: undefined, episode: undefined }); // from cache
+  });
+
+  test('throws with invalid tmdb id', async () => {
+    await expect(getImdbIdFromTmdbId(ctx, fetcher, { id: 12345678, series: 1, episode: 1 })).rejects.toThrow(Error);
+  });
+});
diff --git a/src/utils/tmdb.ts b/src/utils/tmdb.ts
index e6aa518..f3d14f7 100644
--- a/src/utils/tmdb.ts
+++ b/src/utils/tmdb.ts
@@ -5,10 +5,32 @@ import { envGet } from './env';
 
 export interface TmdbId { id: number; series: number | undefined; episode: number | undefined }
 
-export const getTmdbIdFromImdbId = async (ctx: Context, fetcher: Fetcher, imdbId: ImdbId): Promise<TmdbId> => {
-  const url = new URL(`https://api.themoviedb.org/3/find/${imdbId.id}?external_source=imdb_id`);
+interface FindResponsePartial {
+  movie_results: {
+    id: number;
+  }[];
+  tv_results: {
+    id: number;
+  }[];
+}
+
+interface ExternalIdsResponsePartial {
+  imdb_id: string;
+}
+
+const fetch = async (ctx: Context, fetcher: Fetcher, url: URL): Promise<unknown> => {
   const config = { 'headers': { Authorization: 'Bearer ' + envGet('TMDB_ACCESS_TOKEN') }, 'Content-Type': 'application/json' };
-  const response = JSON.parse(await fetcher.text(ctx, url, config));
+
+  return JSON.parse(await fetcher.text(ctx, url, config));
+};
+
+const imdbTmdbMap = new Map<string, number>();
+export const getTmdbIdFromImdbId = async (ctx: Context, fetcher: Fetcher, imdbId: ImdbId): Promise<TmdbId> => {
+  if (imdbTmdbMap.has(imdbId.id)) {
+    return { id: imdbTmdbMap.get(imdbId.id) as number, series: imdbId.series, episode: imdbId.episode };
+  }
+
+  const response = await fetch(ctx, fetcher, new URL(`https://api.themoviedb.org/3/find/${imdbId.id}?external_source=imdb_id`)) as FindResponsePartial;
 
   const id = (imdbId.series ? response.tv_results[0] : response.movie_results[0])?.id;
 
@@ -16,5 +38,20 @@ export const getTmdbIdFromImdbId = async (ctx: Context, fetcher: Fetcher, imdbId
     throw new Error(`Could not get TMDB ID of IMDb ID "${imdbId.id}"`);
   }
 
+  imdbTmdbMap.set(imdbId.id, id);
   return { id, series: imdbId.series, episode: imdbId.episode };
 };
+
+const tmdbImdbMap = new Map<number, string>();
+export const getImdbIdFromTmdbId = async (ctx: Context, fetcher: Fetcher, tmdbId: TmdbId): Promise<ImdbId> => {
+  if (tmdbImdbMap.has(tmdbId.id)) {
+    return { id: tmdbImdbMap.get(tmdbId.id) as string, series: tmdbId.series, episode: tmdbId.episode };
+  }
+
+  const type = tmdbId.series ? 'tv' : 'movie';
+
+  const response = await fetch(ctx, fetcher, new URL(`https://api.themoviedb.org/3/${type}/${tmdbId.id}/external_ids`)) as ExternalIdsResponsePartial;
+
+  tmdbImdbMap.set(tmdbId.id, response.imdb_id);
+  return { id: response.imdb_id, series: tmdbId.series, episode: tmdbId.episode };
+};