diff --git a/src/Client/Adapter/Curl.php b/src/Client/Adapter/Curl.php
index 9d830e4619..1dac31df3d 100644
--- a/src/Client/Adapter/Curl.php
+++ b/src/Client/Adapter/Curl.php
@@ -208,6 +208,18 @@ public function connect($host, $port = 80, $secure = false)
         } else {
             $connectTimeout = null;
         }
+
+        if ($connectTimeout !== null && (! is_int($connectTimeout) || ! is_numeric($connectTimeout))) {
+            throw new AdapterException\InvalidArgumentException(sprintf(
+                'integer or numeric string expected, got %s',
+                gettype($connectTimeout)
+            ));
+        }
+
+        if ($connectTimeout !== null) {
+            $connectTimeout = (int) $connectTimeout;
+        }
+
         if ($connectTimeout !== null) {
             if (defined('CURLOPT_CONNECTTIMEOUT_MS')) {
                 curl_setopt($this->curl, CURLOPT_CONNECTTIMEOUT_MS, $connectTimeout * 1000);
diff --git a/src/Client/Adapter/Socket.php b/src/Client/Adapter/Socket.php
index 2319a4785f..26a17217a8 100644
--- a/src/Client/Adapter/Socket.php
+++ b/src/Client/Adapter/Socket.php
@@ -262,6 +262,14 @@ public function connect($host, $port = 80, $secure = false)
             } else {
                 $connectTimeout = $this->config['timeout'];
             }
+
+            if ($connectTimeout !== null && (! is_int($connectTimeout) || ! is_numeric($connectTimeout))) {
+                throw new AdapterException\InvalidArgumentException(sprintf(
+                    'integer or numeric string expected, got %s',
+                    gettype($connectTimeout)
+                ));
+            }
+
             ErrorHandler::start();
             $this->socket = stream_socket_client(
                 $host . ':' . $port,
diff --git a/test/Client/CurlTest.php b/test/Client/CurlTest.php
index 0e6c75fc92..6dc81a3fc2 100644
--- a/test/Client/CurlTest.php
+++ b/test/Client/CurlTest.php
@@ -96,6 +96,36 @@ public function testConfigSetAsZendConfig()
         $this->assertEquals($config->nested->item, $hasConfig['nested']['item']);
     }
 
+    public function provideValidTimeoutConfig()
+    {
+        return [
+            'integer' => [10],
+            'numeric' => ['10'],
+        ];
+    }
+
+    /**
+     * @dataProvider provideValidTimeoutConfig
+     */
+    public function testPassValidTimeout($timeout)
+    {
+        $adapter = new Adapter\Curl();
+        $adapter->setOptions(['timeout' => $timeout]);
+
+        $adapter->connect('http://framework.zend.com');
+    }
+
+    public function testThrowInvalidArgumentExceptionOnNonIntegerAndNonNumericStringTimeout()
+    {
+        $adapter = new Adapter\Curl();
+        $adapter->setOptions(['timeout' => 'timeout']);
+
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('integer or numeric string expected, got string');
+
+        $adapter->connect('http://framework.zend.com');
+    }
+
     /**
      * Check that an exception is thrown when trying to set invalid config
      *
diff --git a/test/Client/SocketTest.php b/test/Client/SocketTest.php
index 1610c571f2..e1504041c8 100644
--- a/test/Client/SocketTest.php
+++ b/test/Client/SocketTest.php
@@ -171,6 +171,36 @@ public function testSetConfigInvalidConfig($config)
         $this->_adapter->setOptions($config);
     }
 
+    public function provideValidTimeoutConfig()
+    {
+        return [
+            'integer' => [10],
+            'numeric' => ['10'],
+        ];
+    }
+
+    /**
+     * @dataProvider provideValidTimeoutConfig
+     */
+    public function testPassValidTimeout($timeout)
+    {
+        $adapter = new Adapter\Socket();
+        $adapter->setOptions(['timeout' => $timeout]);
+
+        $adapter->connect('http://framework.zend.com');
+    }
+
+    public function testThrowInvalidArgumentExceptionOnNonIntegerAndNonNumericStringTimeout()
+    {
+        $adapter = new Adapter\Socket();
+        $adapter->setOptions(['timeout' => 'timeout']);
+
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('integer or numeric string expected, got string');
+
+        $adapter->connect('http://framework.zend.com');
+    }
+
     /**
      * Stream context related tests
      */