diff --git a/src/Runtime/RuntimeProcess.php b/src/Runtime/RuntimeProcess.php
index 5f92c93..0ea59b0 100644
--- a/src/Runtime/RuntimeProcess.php
+++ b/src/Runtime/RuntimeProcess.php
@@ -6,6 +6,7 @@
 use Aternos\Taskmaster\Communication\Socket\SocketPair;
 use Aternos\Taskmaster\Communication\StdStreams;
 use Aternos\Taskmaster\TaskmasterOptions;
+use RuntimeException;
 
 /**
  * Class RuntimeProcess
@@ -46,6 +47,9 @@ public function __construct(TaskmasterOptions $options, string $runtimeClass)
             2 => $stdStreams->getStderr(),
             3 => $socketPair->getChildSocket()->getStream(),
         ], $pipes);
+        if (!$this->process) {
+            throw new RuntimeException("Could not open process.");
+        }
         $socketPair->closeChildSocket();
     }
 
@@ -57,6 +61,9 @@ public function __construct(TaskmasterOptions $options, string $runtimeClass)
     public function stop(): bool
     {
         $this->socket->close();
+        if (!$this->process) {
+            return false;
+        }
         $result = proc_terminate($this->process);
         proc_close($this->process);
         $this->process = null;