diff --git a/tests/Bootstrap.php b/tests/Bootstrap.php
index dbb5d4e2b..a95d571cc 100755
--- a/tests/Bootstrap.php
+++ b/tests/Bootstrap.php
@@ -22,7 +22,7 @@ $IS_GITHUB = false;
 
 $temp = \array_keys($_SERVER);
 foreach ($temp as $key) {
-    if (\stripos(\strtolower($key), 'github') !== false) {
+    if (\is_string($key) && \stripos(\strtolower($key), 'github') !== false) {
         $IS_GITHUB = true;
 
         break;
@@ -31,7 +31,7 @@ foreach ($temp as $key) {
 
 if (!$IS_GITHUB) {
     foreach ($_SERVER as $value) {
-        if (\stripos(\strtolower($value), 'github') !== false) {
+        if (\is_string($value) && \stripos(\strtolower($value), 'github') !== false) {
             $IS_GITHUB = true;
 
             break;
@@ -42,7 +42,7 @@ if (!$IS_GITHUB) {
 $temp = \array_keys(\getenv());
 if (!$IS_GITHUB) {
     foreach ($temp as $key) {
-        if (\stripos(\strtolower($key), 'github') !== false) {
+        if (\is_string($key) && \stripos(\strtolower($key), 'github') !== false) {
             $IS_GITHUB = true;
 
             break;
@@ -53,7 +53,7 @@ if (!$IS_GITHUB) {
 $temp = \array_values(\getenv());
 if (!$IS_GITHUB) {
     foreach ($temp as $value) {
-        if (\stripos(\strtolower($value), 'github') !== false) {
+        if (\is_string($value) && \stripos(\strtolower($value), 'github') !== false) {
             $IS_GITHUB = true;
 
             break;