diff --git a/tests/unit/workflow/engine/src/ProcessMaker/Validation/ValidationUploadedFilesTest.php b/tests/unit/workflow/engine/src/ProcessMaker/Validation/ValidationUploadedFilesTest.php
new file mode 100644
index 000000000..171c41f27
--- /dev/null
+++ b/tests/unit/workflow/engine/src/ProcessMaker/Validation/ValidationUploadedFilesTest.php
@@ -0,0 +1,125 @@
+<?php
+
+namespace Tests\unit\workflow\engine\src\ProcessMaker\Validation;
+
+use ProcessMaker\Validation\ValidationUploadedFiles;
+use Tests\TestCase;
+
+/**
+ * @coversDefaultClass \ProcessMaker\Validation\ValidationUploadedFiles
+ */
+class ValidationUploadedFilesTest extends TestCase
+{
+
+    /**
+     * It copies the images for the test
+     */
+    public function setUp()
+    {
+        parent::setUp(); // TODO: Change the autogenerated stub
+        copy(PATH_HTML . 'images/1.png', PATH_DATA . '1.PNG');
+        copy(PATH_HTML . 'images/1.png', PATH_DATA . '1.png');
+        copy(PATH_HTML . 'images/1.png', PATH_DATA . '1.PnG');
+    }
+
+    /**
+     * It tests the runRules method when the file extension is in upper case
+     *
+     * @covers ::runRules
+     * @test
+     */
+    public function it_should_test_the_run_rules_method_in_upper_case()
+    {
+        // Create the file
+        $file = [
+            "filename" => "1.PNG",
+            "path" => PATH_DATA . "1.PNG"
+        ];
+
+        // Create the ValidationUploadedFiles object
+        $validation = new ValidationUploadedFiles();
+
+        // Call the runRules method
+        $result = $validation->runRules($file);
+
+        // Asserts the validation did not fail
+        $this->assertFalse($result->fails());
+
+        // Asserts there is no a message
+        $this->assertEmpty($result->getMessage());
+
+        // Asserts the status is 0
+        $this->assertEquals(0, $result->getStatus());
+    }
+
+    /**
+     * It tests the runRules method when the file extension is in lower case
+     *
+     * @covers ::runRules
+     * @test
+     */
+    public function it_should_test_the_run_rules_method_in_lower_case()
+    {
+        // Create the file
+        $file = [
+            "filename" => "1.png",
+            "path" => PATH_DATA . "1.png"
+        ];
+
+        // Create the ValidationUploadedFiles object
+        $validation = new ValidationUploadedFiles();
+
+        // Call the runRules method
+        $result = $validation->runRules($file);
+
+        // Asserts the validation did not fail
+        $this->assertFalse($result->fails());
+
+        // Asserts there is no a message
+        $this->assertEmpty($result->getMessage());
+
+        // Asserts the status is 0
+        $this->assertEquals(0, $result->getStatus());
+    }
+
+    /**
+     * It tests the runRules method when the file extension is in upper and lower case
+     *
+     * @covers ::runRules
+     * @test
+     */
+    public function it_should_test_the_run_rules_method_in_upper_and_lower_case()
+    {
+        // Create the file
+        $file = [
+            "filename" => "1.PnG",
+            "path" => PATH_DATA . "1.PnG"
+        ];
+
+        // Create the ValidationUploadedFiles object
+        $validation = new ValidationUploadedFiles();
+
+        // Call the runRules method
+        $result = $validation->runRules($file);
+
+        // Asserts the validation did not fail
+        $this->assertFalse($result->fails());
+
+        // Asserts there is no a message
+        $this->assertEmpty($result->getMessage());
+
+        // Asserts the status is 0
+        $this->assertEquals(0, $result->getStatus());
+    }
+
+    /**
+     * It deletes the images created
+     */
+    public function tearDown()
+    {
+        parent::tearDown(); // TODO: Change the autogenerated stub
+        unlink(PATH_DATA . '1.PNG');
+        unlink(PATH_DATA . '1.png');
+        unlink(PATH_DATA . '1.PnG');
+    }
+}
\ No newline at end of file
diff --git a/workflow/engine/src/ProcessMaker/Validation/ValidationUploadedFiles.php b/workflow/engine/src/ProcessMaker/Validation/ValidationUploadedFiles.php
index f2abeca72..8f028e0de 100644
--- a/workflow/engine/src/ProcessMaker/Validation/ValidationUploadedFiles.php
+++ b/workflow/engine/src/ProcessMaker/Validation/ValidationUploadedFiles.php
@@ -44,7 +44,7 @@ class ValidationUploadedFiles
         $validator->addRule()
                 ->validate($file, function($file) {
                     $filesystem = new Filesystem();
-                    $extension = $filesystem->extension($file->filename);
+                    $extension = strtolower($filesystem->extension($file->filename));
 
                     return Bootstrap::getDisablePhpUploadExecution() === 1 && $extension === 'php';
                 })
@@ -112,7 +112,7 @@ class ValidationUploadedFiles
                         return false;
                     }
 
-                    $extension = $filesystem->extension($file->filename);
+                    $extension = strtolower($filesystem->extension($file->filename));
                     $mimeType = $filesystem->mimeType($path);
 
                     $file = new File($path);