diff --git a/sec-gemini-ts/src/session.ts b/sec-gemini-ts/src/session.ts
index 4747fc7..0eb63d4 100644
--- a/sec-gemini-ts/src/session.ts
+++ b/sec-gemini-ts/src/session.ts
@@ -286,8 +286,8 @@ export class InteractiveSession {
     } = options;
 
     // --- Validation ---
-    if (ttl <= MIN_TTL_SECONDS) {
-      throw new Error(`TTL must be greater than ${MIN_TTL_SECONDS} seconds.`);
+    if (ttl < MIN_TTL_SECONDS) {
+      throw new Error(`TTL must be at least ${MIN_TTL_SECONDS} seconds.`);
     }
     if (!model || !model.model_string) {
       throw new Error('Valid ModelInfoInput object is required for registration.');
@@ -499,8 +499,8 @@ export class InteractiveSession {
 
     // Apply TTL update logic
     if (ttl > 0) {
-      if (ttl <= MIN_TTL_SECONDS) {
-        throw new Error(`TTL must be greater than ${MIN_TTL_SECONDS} seconds`);
+      if (ttl < MIN_TTL_SECONDS) {
+        throw new Error(`TTL must be at least ${MIN_TTL_SECONDS} seconds`);
       }
       updatePayload.ttl = ttl;
     }
diff --git a/sec-gemini-ts/tests/session.test.ts b/sec-gemini-ts/tests/session.test.ts
index 008c79e..0709cf8 100644
--- a/sec-gemini-ts/tests/session.test.ts
+++ b/sec-gemini-ts/tests/session.test.ts
@@ -134,6 +134,20 @@ describe('Session', () => {
     jest.clearAllTimers();
     openedUrl = '';
   });
+  test('should throw error when TTL is below minimum', async () => {
+    const registerPromise = session.register({
+      ttl: 299,
+      model: model,
+    });
+    await expect(registerPromise).rejects.toThrow('TTL must be at least 300 seconds.');
+  });
+  test('should register session when TTL is exactly 300', async () => {
+    const registerPromise = session.register({
+      ttl: 300,
+      model: model,
+    });
+    await expect(registerPromise).resolves.not.toThrow();
+  });
   test('should throw error when registering session', async () => {
     // Throw error during post request to register session.
     registerSession.mockImplementationOnce(() => {