diff --git a/src/Process.php b/src/Process.php
index 2a275e9..d06b303 100644
--- a/src/Process.php
+++ b/src/Process.php
@@ -199,11 +199,20 @@ public function start(LoopInterface $loop = null, $interval = 0.1)
             $options['suppress_errors'] = true;
         }
 
+        $errstr = '';
+        \set_error_handler(function ($_, $error) use (&$errstr) {
+            // Match errstr from PHP's warning message.
+            // proc_open(/dev/does-not-exist): Failed to open stream: No such file or directory
+            $errstr = $error;
+        });
+
+        $pipes = array();
         $this->process = @\proc_open($cmd, $fdSpec, $pipes, $this->cwd, $this->env, $options);
 
+        \restore_error_handler();
+
         if (!\is_resource($this->process)) {
-            $error = \error_get_last();
-            throw new \RuntimeException('Unable to launch a new process: ' . $error['message']);
+            throw new \RuntimeException('Unable to launch a new process: ' . $errstr);
         }
 
         // count open process pipes and await close event for each to drain buffers before detecting exit
diff --git a/tests/AbstractProcessTest.php b/tests/AbstractProcessTest.php
index d41de2e..de7da35 100644
--- a/tests/AbstractProcessTest.php
+++ b/tests/AbstractProcessTest.php
@@ -126,7 +126,7 @@ public function testStartWithCustomPipesWillAssignPipes()
         $this->assertInstanceOf('React\Stream\WritableStreamInterface', $process->pipes[3]);
     }
 
-    public function testStartWithInvalidFileDescriptorPathWillThrow()
+    public function testStartWithInvalidFileDescriptorPathWillThrowWithoutCallingCustomErrorHandler()
     {
         if (defined('HHVM_VERSION')) {
             $this->markTestSkipped('Not supported on legacy HHVM');
@@ -138,8 +138,22 @@ public function testStartWithInvalidFileDescriptorPathWillThrow()
 
         $process = new Process('exit 0', null, null, $fds);
 
+        $error = null;
+        set_error_handler(function ($_, $errstr) use (&$error) {
+            $error = $errstr;
+        });
+
         $this->setExpectedException('RuntimeException', 'No such file or directory');
-        $process->start($this->createLoop());
+
+        try {
+            $process->start($this->createLoop());
+            restore_error_handler();
+        } catch (\Exception $e) {
+            restore_error_handler();
+            $this->assertNull($error);
+
+            throw $e;
+        }
     }
 
     public function testStartWithExcessiveNumberOfFileDescriptorsWillThrow()