diff --git a/src/parser/xhpast/api/__tests__/XHPASTTreeTestCase.php b/src/parser/xhpast/api/__tests__/XHPASTTreeTestCase.php
--- a/src/parser/xhpast/api/__tests__/XHPASTTreeTestCase.php
+++ b/src/parser/xhpast/api/__tests__/XHPASTTreeTestCase.php
@@ -7,14 +7,14 @@
 
   public function testEvalStaticString() {
     $this->assertEval(1,    '1');
-    $this->assertEval("a",  '"a"');
+    $this->assertEval('a',  '"a"');
     $this->assertEval(-1.1, '-1.1');
     $this->assertEval(
        array('foo', 'bar', -1, +2, -3.4, +4.3, 1e10, 1e-5, -2.3e7),
       "array('foo', 'bar', -1, +2, -3.4, +4.3, 1e10, 1e-5, -2.3e7)");
     $this->assertEval(
        array(),
-      "array()");
+      'array()');
     $this->assertEval(
        array(42 => 7, 'a' => 5, 1, 2, 3, 4, 1 => 'goo'),
       "array(42 => 7, 'a' => 5, 1, 2, 3, 4, 1 => 'goo')");
@@ -23,7 +23,7 @@
       "array('a' => 'a', 'b' => array(1, 2, array(3)))");
     $this->assertEval(
        array(true, false, null),
-      "array(true, false, null)");
+      'array(true, false, null)');
 
     // Duplicate keys
     $this->assertEval(
@@ -33,11 +33,11 @@
     $this->assertEval('simple string', "'simple string'");
     $this->assertEval('42', "'42'");
     $this->assertEval('binary string', "b'binary string'");
-    $this->assertEval(3.1415926, "3.1415926");
+    $this->assertEval(3.1415926, '3.1415926');
     $this->assertEval(42, '42');
     $this->assertEval(
        array(2147483648, 2147483647, -2147483648, -2147483647),
-      "array(2147483648, 2147483647, -2147483648, -2147483647)");
+      'array(2147483648, 2147483647, -2147483648, -2147483647)');
 
     $this->assertEval(INF, 'INF');
     $this->assertEval(-INF, '-INF');