diff --git a/Process.php b/Process.php
index cd84cd44..520794ed 100644
--- a/Process.php
+++ b/Process.php
@@ -476,7 +476,7 @@ public function getExitCodeText()
      */
     public function isSuccessful()
     {
-        return 0 == $this->getExitCode();
+        return 0 === $this->getExitCode();
     }
 
     /**
diff --git a/Tests/AbstractProcessTest.php b/Tests/AbstractProcessTest.php
index e78374ae..2fc2ea77 100644
--- a/Tests/AbstractProcessTest.php
+++ b/Tests/AbstractProcessTest.php
@@ -298,6 +298,18 @@ public function testIsSuccessful()
         $this->assertTrue($process->isSuccessful());
     }
 
+    public function testIsSuccessfulOnlyAfterTerminated()
+    {
+        $process = $this->getProcess('sleep 1');
+        $process->start();
+        while ($process->isRunning()) {
+            $this->assertFalse($process->isSuccessful());
+            usleep(300000);
+        }
+
+        $this->assertTrue($process->isSuccessful());
+    }
+
     public function testIsNotSuccessful()
     {
         $process = $this->getProcess('php -r "sleep(4);"');
diff --git a/Tests/SigchildDisabledProcessTest.php b/Tests/SigchildDisabledProcessTest.php
index 0ec96f47..c82304b5 100644
--- a/Tests/SigchildDisabledProcessTest.php
+++ b/Tests/SigchildDisabledProcessTest.php
@@ -96,6 +96,14 @@ public function testIsSuccessful()
         parent::testIsSuccessful();
     }
 
+    /**
+     * @expectedException \Symfony\Component\Process\Exception\RuntimeException
+     */
+    public function testIsSuccessfulOnlyAfterTerminated()
+    {
+        parent::testIsSuccessfulOnlyAfterTerminated();
+    }
+
     /**
      * @expectedException \Symfony\Component\Process\Exception\RuntimeException
      */