diff --git a/evals/grep_search_functionality.eval.ts b/evals/grep_search_functionality.eval.ts
index 5c1da827e1..46dad0ae22 100644
--- a/evals/grep_search_functionality.eval.ts
+++ b/evals/grep_search_functionality.eval.ts
@@ -179,4 +179,24 @@ describe('grep_search_functionality', () => {
       });
     },
   });
+
+  evalTest('USUALLY_PASSES', {
+    suiteName: 'default',
+    suiteType: 'behavioral',
+    name: 'should find files in hidden directories',
+    files: {
+      '.hidden_dir/system.md':
+        'Instructional Conversion and Integration Protocol',
+      'visible_dir/normal.txt': 'nothing to see here',
+    },
+    prompt: 'Find "Instructional Conversion and Integration Protocol"',
+    assert: async (rig: TestRig, result: string) => {
+      await rig.waitForToolCall('grep_search');
+      assertModelHasOutput(result);
+      checkModelOutputContent(result, {
+        expectedContent: [/\.hidden_dir\/system\.md/],
+        testName: `${TEST_PREFIX}hidden directory search`,
+      });
+    },
+  });
 });
diff --git a/packages/core/src/tools/ripGrep.test.ts b/packages/core/src/tools/ripGrep.test.ts
index bd3cd21189..e1da811fd9 100644
--- a/packages/core/src/tools/ripGrep.test.ts
+++ b/packages/core/src/tools/ripGrep.test.ts
@@ -1330,6 +1330,7 @@ describe('RipGrepTool', () => {
       const result = await invocation.execute({ abortSignal });
 
       const spawnArgs = mockSpawn.mock.calls[0][1];
+      expect(spawnArgs).toContain('--hidden');
       expect(spawnArgs).toContain('--fixed-strings');
       expect(spawnArgs).toContain('--regexp');
       expect(spawnArgs).toContain('hello.world');
@@ -1777,6 +1778,7 @@ describe('RipGrepTool', () => {
       await invocation.execute({ abortSignal });
 
       const spawnArgs = mockSpawn.mock.calls[0][1];
+      expect(spawnArgs).toContain('--hidden');
       expect(spawnArgs).toContain('--max-count');
       expect(spawnArgs).toContain('1');
     });
diff --git a/packages/core/src/tools/ripGrep.ts b/packages/core/src/tools/ripGrep.ts
index c2ae482289..a72fb059ed 100644
--- a/packages/core/src/tools/ripGrep.ts
+++ b/packages/core/src/tools/ripGrep.ts
@@ -402,7 +402,7 @@ class GrepToolInvocation extends BaseToolInvocation<
 
     const searchPaths = Array.isArray(path) ? path : [path];
 
-    const rgArgs = ['--json'];
+    const rgArgs = ['--json', '--hidden'];
 
     if (!case_sensitive) {
       rgArgs.push('--ignore-case');