diff --git a/modules/openapi-generator/src/main/resources/php/Configuration.mustache b/modules/openapi-generator/src/main/resources/php/Configuration.mustache
index 32de830191c..35a4ab5c5e8 100644
--- a/modules/openapi-generator/src/main/resources/php/Configuration.mustache
+++ b/modules/openapi-generator/src/main/resources/php/Configuration.mustache
@@ -474,7 +474,7 @@ class Configuration
         $hosts = $this->getHostSettings();
 
         // check array index out of bound
-        if ($index < 0 || $index > sizeof($hosts)) {
+        if ($index < 0 || $index >= sizeof($hosts)) {
             throw new \InvalidArgumentException("Invalid index $index when selecting the host. Must be less than ".sizeof($hosts));
         }
 
diff --git a/samples/client/petstore/php/OpenAPIClient-php/lib/Configuration.php b/samples/client/petstore/php/OpenAPIClient-php/lib/Configuration.php
index 641f72e7663..e9c5da06eab 100644
--- a/samples/client/petstore/php/OpenAPIClient-php/lib/Configuration.php
+++ b/samples/client/petstore/php/OpenAPIClient-php/lib/Configuration.php
@@ -458,7 +458,7 @@ class Configuration
         $hosts = $this->getHostSettings();
 
         // check array index out of bound
-        if ($index < 0 || $index > sizeof($hosts)) {
+        if ($index < 0 || $index >= sizeof($hosts)) {
             throw new \InvalidArgumentException("Invalid index $index when selecting the host. Must be less than ".sizeof($hosts));
         }
 
diff --git a/samples/openapi3/client/petstore/php/OpenAPIClient-php/lib/Configuration.php b/samples/openapi3/client/petstore/php/OpenAPIClient-php/lib/Configuration.php
index 42a68f7a3e0..a45e571f6fb 100644
--- a/samples/openapi3/client/petstore/php/OpenAPIClient-php/lib/Configuration.php
+++ b/samples/openapi3/client/petstore/php/OpenAPIClient-php/lib/Configuration.php
@@ -491,7 +491,7 @@ class Configuration
         $hosts = $this->getHostSettings();
 
         // check array index out of bound
-        if ($index < 0 || $index > sizeof($hosts)) {
+        if ($index < 0 || $index >= sizeof($hosts)) {
             throw new \InvalidArgumentException("Invalid index $index when selecting the host. Must be less than ".sizeof($hosts));
         }
 
diff --git a/samples/openapi3/client/petstore/php/OpenAPIClient-php/tests/ConfigurationTest.php b/samples/openapi3/client/petstore/php/OpenAPIClient-php/tests/ConfigurationTest.php
index 983b871fd40..4b2738841b4 100644
--- a/samples/openapi3/client/petstore/php/OpenAPIClient-php/tests/ConfigurationTest.php
+++ b/samples/openapi3/client/petstore/php/OpenAPIClient-php/tests/ConfigurationTest.php
@@ -41,6 +41,17 @@ class ConfigurationTest extends TestCase
         $this->assertSame("http://dev-petstore.swagger.io:8080/v2", $url);
     }
 
+    /**
+     * Test invalid index
+     * @expectedException InvalidArgumentException
+     * @expectedExceptionMessage Invalid index 2 when selecting the host. Must be less than 2
+     */
+    public function testInvalidIndex()
+    {
+        $config = new Configuration();
+        $url = $config->getHostFromSettings(2);
+    }
+
     /**
      * Test host settings with invalid vaues
      * @expectedException InvalidArgumentException