diff --git a/classes/mutex/SpinlockMutex.php b/classes/mutex/SpinlockMutex.php
index be51939e..6e156514 100644
--- a/classes/mutex/SpinlockMutex.php
+++ b/classes/mutex/SpinlockMutex.php
@@ -22,7 +22,7 @@ abstract class SpinlockMutex extends LockMutex
     /**
      * The prefix for the lock key.
      */
-    private const PREFIX = 'lock_';
+    private const PREFIX = 'php_malkusch_lock:';
 
     /**
      * @var int The timeout in seconds a lock may live.
diff --git a/tests/mutex/MemcachedMutexTest.php b/tests/mutex/MemcachedMutexTest.php
index b18e473f..4091942e 100644
--- a/tests/mutex/MemcachedMutexTest.php
+++ b/tests/mutex/MemcachedMutexTest.php
@@ -45,7 +45,7 @@ public function testFailAcquireLock()
 
         $this->memcached->expects($this->atLeastOnce())
             ->method('add')
-            ->with('lock_test', true, 2)
+            ->with('php_malkusch_lock:test', true, 2)
             ->willReturn(false);
 
         $this->mutex->synchronized(function (): void {
@@ -62,12 +62,12 @@ public function testFailReleasingLock()
 
         $this->memcached->expects($this->once())
             ->method('add')
-            ->with('lock_test', true, 2)
+            ->with('php_malkusch_lock:test', true, 2)
             ->willReturn(true);
 
         $this->memcached->expects($this->once())
             ->method('delete')
-            ->with('lock_test')
+            ->with('php_malkusch_lock:test')
             ->willReturn(false);
 
         $this->mutex->synchronized(function (): void {
diff --git a/tests/mutex/PredisMutexTest.php b/tests/mutex/PredisMutexTest.php
index 81a53f0f..13bcf6e7 100644
--- a/tests/mutex/PredisMutexTest.php
+++ b/tests/mutex/PredisMutexTest.php
@@ -56,7 +56,7 @@ public function testAddFailsToSetKey()
     {
         $this->client->expects($this->atLeastOnce())
             ->method('set')
-            ->with('lock_test', $this->isType('string'), 'EX', 4, 'NX')
+            ->with('php_malkusch_lock:test', $this->isType('string'), 'EX', 4, 'NX')
             ->willReturn(null);
 
         $this->logger->expects($this->never())
@@ -78,7 +78,7 @@ public function testAddErrors()
     {
         $this->client->expects($this->atLeastOnce())
             ->method('set')
-            ->with('lock_test', $this->isType('string'), 'EX', 4, 'NX')
+            ->with('php_malkusch_lock:test', $this->isType('string'), 'EX', 4, 'NX')
             ->willThrowException($this->createMock(PredisException::class));
 
         $this->logger->expects($this->once())
@@ -98,12 +98,12 @@ public function testWorksNormally()
     {
         $this->client->expects($this->atLeastOnce())
             ->method('set')
-            ->with('lock_test', $this->isType('string'), 'EX', 4, 'NX')
+            ->with('php_malkusch_lock:test', $this->isType('string'), 'EX', 4, 'NX')
             ->willReturnSelf();
 
         $this->client->expects($this->once())
             ->method('eval')
-            ->with($this->anything(), 1, 'lock_test', $this->isType('string'))
+            ->with($this->anything(), 1, 'php_malkusch_lock:test', $this->isType('string'))
             ->willReturn(true);
 
         $executed = false;
@@ -122,12 +122,12 @@ public function testEvalScriptFails()
     {
         $this->client->expects($this->atLeastOnce())
             ->method('set')
-            ->with('lock_test', $this->isType('string'), 'EX', 4, 'NX')
+            ->with('php_malkusch_lock:test', $this->isType('string'), 'EX', 4, 'NX')
             ->willReturnSelf();
 
         $this->client->expects($this->once())
             ->method('eval')
-            ->with($this->anything(), 1, 'lock_test', $this->isType('string'))
+            ->with($this->anything(), 1, 'php_malkusch_lock:test', $this->isType('string'))
             ->willThrowException($this->createMock(PredisException::class));
 
         $this->logger->expects($this->once())