diff --git a/CHANGELOG.md b/CHANGELOG.md
index 552b6cf..318c905 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 - Enh #62: Remove not need casting to array in private method `Memcached::iterableToArray()` (@vjik)
 - Enh #62: Improve list of memcached server validation (@vjik) 
+- Enh #62: Check key type when multiple keys passed (@vjik) 
 
 ## 2.0.0 February 15, 2023
 
diff --git a/src/Memcached.php b/src/Memcached.php
index 8e0351d..3dbdc74 100644
--- a/src/Memcached.php
+++ b/src/Memcached.php
@@ -269,9 +269,20 @@ private function validateKey(string $key): void
         }
     }
 
+    /**
+     * @psalm-assert string[] $keys
+     */
     private function validateKeys(array $keys): void
     {
         foreach ($keys as $key) {
+            if (!is_string($key)) {
+                throw new InvalidArgumentException(
+                    sprintf(
+                        'Invalid key type. Expected string, got %s.',
+                        get_debug_type($key)
+                    )
+                );
+            }
             $this->validateKey($key);
         }
     }
diff --git a/tests/MemcachedTest.php b/tests/MemcachedTest.php
index b836659..601f0fd 100644
--- a/tests/MemcachedTest.php
+++ b/tests/MemcachedTest.php
@@ -219,6 +219,15 @@ public function testGetMultiple(): void
         $this->assertSameExceptObject($data, $cache->getMultiple(array_map('\strval', array_keys($data))));
     }
 
+    public function testGetMultipleWithNotStringKey()
+    {
+        $cache = $this->createCacheInstance();
+
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Invalid key type. Expected string, got int.');
+        $cache->getMultiple(['test', 1]);
+    }
+
     public function testDeleteMultiple(): void
     {
         $cache = $this->createCacheInstance();