diff --git a/src/Common/CommandArguments.php b/src/Common/CommandArguments.php
index d1984cff4..4fc3a90f8 100644
--- a/src/Common/CommandArguments.php
+++ b/src/Common/CommandArguments.php
@@ -40,7 +40,7 @@ public function args($args)
         if (!is_array($args)) {
             $args = $func_args;
         }
-        $this->arguments .= ' ' . implode(' ', array_map(static::class . '::escape', $args));
+        $this->arguments .= ' ' . implode(' ', array_map([static::class, 'escape'], $args));
         return $this;
     }
 
diff --git a/tests/phpunit/Task/ExecTest.php b/tests/phpunit/Task/ExecTest.php
new file mode 100644
index 000000000..cd8d958f4
--- /dev/null
+++ b/tests/phpunit/Task/ExecTest.php
@@ -0,0 +1,19 @@
+<?php
+
+namespace phpunit\Task;
+
+use PHPUnit\Framework\TestCase;
+
+class ExecTest extends TestCase
+{
+
+    // tests
+    public function testBasicCommand()
+    {
+        $this->assertSame(
+            'ls',
+            (new \Robo\Task\Base\Exec('ls'))
+                ->getCommand()
+        );
+    }
+}