diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4715c7a..b3fe012 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [5.1.1] - 2026-10-26
+### Fixed
+- Disposing a `pettyCache.mutex.lock()` handle no longer rejects when Redis fails. The error is ignored and the lock expires via its TTL, as with the semaphore functions. Before, an `await using` block threw after its work succeeded, or wrapped its own error in a `SuppressedError`.
+
 ## [5.1.0] - 2026-10-26
 ### Added
 - `pettyCache.mutex.lock()` resolves with a lock handle. Declare it with `await using` to release the lock when the block exits, even when it throws. The handle only releases its own lock: if the TTL expired and another caller acquired the lock, disposing the handle leaves the newer lock in place.
diff --git a/README.md b/README.md
index 8782a09..b507184 100644
--- a/README.md
+++ b/README.md
@@ -322,7 +322,7 @@ async function doWork() {
 }
 ```
 
-The handle only releases its own lock. If the TTL expired and another caller acquired the lock, disposing the handle leaves the newer lock in place. Without `await using`, release the lock with `await lock[Symbol.asyncDispose]()`.
+The handle only releases its own lock. If the TTL expired and another caller acquired the lock, disposing the handle leaves the newer lock in place. Releasing never rejects: if Redis fails, the error is ignored and the lock expires via its TTL. Without `await using`, release the lock with `await lock[Symbol.asyncDispose]()`.
 
 **Options**
 
diff --git a/index.js b/index.js
index 57d4e28..4026a6b 100644
--- a/index.js
+++ b/index.js
@@ -503,8 +503,9 @@ function PettyCache(options) {
 
                 return {
                     [Symbol.asyncDispose]: async () => {
-                        // Compare-and-delete, so a holder whose TTL expired can't release a newer holder's lock
-                        await redisClient.eval('if redis.call("get", KEYS[1]) == ARGV[1] then return redis.call("del", KEYS[1]) end return 0', { arguments: [value], keys: [key] });
+                        // Compare-and-delete, so a holder whose TTL expired can't release a newer holder's lock.
+                        // Release errors are ignored; the mutex lock expires via its TTL
+                        await redisClient.eval('if redis.call("get", KEYS[1]) == ARGV[1] then return redis.call("del", KEYS[1]) end return 0', { arguments: [value], keys: [key] }).catch(() => {});
                     }
                 };
             };
diff --git a/package.json b/package.json
index cf58f32..512fa54 100644
--- a/package.json
+++ b/package.json
@@ -29,5 +29,5 @@
         "test": "node --test --test-force-exit --test-reporter=spec",
         "test:only": "node --test --test-force-exit --test-only --test-reporter=spec"
     },
-    "version": "5.1.0"
+    "version": "5.1.1"
 }
diff --git a/test/index.js b/test/index.js
index 712ff6e..07e1aba 100644
--- a/test/index.js
+++ b/test/index.js
@@ -1834,7 +1834,7 @@ test('PettyCache.mutex.unlock should return error if Redis DEL fails', async ()
     stubClient.del = originalDel;
 });
 
-test('PettyCache.mutex.lock handle should return error if Redis EVAL fails', async () => {
+test('PettyCache.mutex.lock handle should ignore Redis EVAL errors', async () => {
     const stubClient = redis.createClient();
     const originalEval = stubClient.eval.bind(stubClient);
 
@@ -1843,10 +1843,14 @@ test('PettyCache.mutex.lock handle should return error if Redis EVAL fails', asy
     const pettyCache = new PettyCache(stubClient);
     const lock = await pettyCache.mutex.lock(Math.random().toString());
 
-    await assert.rejects(
-        lock[Symbol.asyncDispose](),
-        { message: 'Redis EVAL error' }
-    );
+    await assert.doesNotReject(lock[Symbol.asyncDispose]());
+
+    // The await using block's own error comes through, not wrapped in a SuppressedError
+    await assert.rejects(async () => {
+        await using lock = await pettyCache.mutex.lock(Math.random().toString());
+
+        throw new Error('Work failed');
+    }, { message: 'Work failed', name: 'Error' });
 
     stubClient.eval = originalEval;
 });