diff --git a/src/processors/__tests__/snapshot-processor.test.js b/src/processors/__tests__/snapshot-processor.test.ts
similarity index 86%
rename from src/processors/__tests__/snapshot-processor.test.js
rename to src/processors/__tests__/snapshot-processor.test.ts
index 787f6182d..b4a807af5 100644
--- a/src/processors/__tests__/snapshot-processor.test.js
+++ b/src/processors/__tests__/snapshot-processor.test.ts
@@ -22,11 +22,9 @@ describe('snapshot-processor', () => {
     it('should only return messages about snapshot specific rules', () => {
       const { postprocess } = snapshotProcessor;
       const result = postprocess([
-        [
-          { ruleId: 'no-console' },
-          { ruleId: 'global-require' },
-          { ruleId: 'jest/no-large-snapshots' },
-        ],
+        ['no-console', 'global-require', 'jest/no-large-snapshots'].map(
+          ruleId => ({ ruleId }),
+        ),
       ]);
 
       expect(result).toEqual([{ ruleId: 'jest/no-large-snapshots' }]);
diff --git a/src/processors/snapshot-processor.js b/src/processors/snapshot-processor.js
deleted file mode 100644
index f49843073..000000000
--- a/src/processors/snapshot-processor.js
+++ /dev/null
@@ -1,8 +0,0 @@
-// https://eslint.org/docs/developer-guide/working-with-plugins#processors-in-plugins
-export const preprocess = source => [source];
-
-export const postprocess = messages =>
-  messages[0].filter(
-    // snapshot files should only be linted with snapshot specific rules
-    message => message.ruleId === 'jest/no-large-snapshots',
-  );
diff --git a/src/processors/snapshot-processor.ts b/src/processors/snapshot-processor.ts
new file mode 100644
index 000000000..8bf53fc33
--- /dev/null
+++ b/src/processors/snapshot-processor.ts
@@ -0,0 +1,9 @@
+// https://eslint.org/docs/developer-guide/working-with-plugins#processors-in-plugins
+// https://github.com/typescript-eslint/typescript-eslint/issues/808
+
+type PostprocessMessage = { ruleId: string };
+
+export const preprocess = (source: string): string[] => [source];
+export const postprocess = (messages: PostprocessMessage[][]) =>
+  // snapshot files should only be linted with snapshot specific rules
+  messages[0].filter(message => message.ruleId === 'jest/no-large-snapshots');