diff --git a/core/modules/image/image.module b/core/modules/image/image.module
index 29a18a7..a7696a6 100644
--- a/core/modules/image/image.module
+++ b/core/modules/image/image.module
@@ -562,7 +562,7 @@ function image_style_deliver($style, $scheme) {
 
   // Don't try to generate file if source is missing.
   if (!file_exists($image_uri)) {
-    watchdog('image', 'Unable to generate the derived image from image at %path.', array('%path' => $derivative_uri));
+    watchdog('image', 'Source image at %source_image_path not found while trying to generate derivative image at %derivative_path.',  array('%source_image_path' => $image_uri, '%derivative_path' => $derivative_uri));
     return new Response(t('Error generating image, missing source file.'), 404);
   }
 
diff --git a/core/modules/image/lib/Drupal/image/Tests/ImageStylesPathAndUrlTest.php b/core/modules/image/lib/Drupal/image/Tests/ImageStylesPathAndUrlTest.php
index 07ea3fb..ae550ae 100644
--- a/core/modules/image/lib/Drupal/image/Tests/ImageStylesPathAndUrlTest.php
+++ b/core/modules/image/lib/Drupal/image/Tests/ImageStylesPathAndUrlTest.php
@@ -91,6 +91,16 @@ function testImageStyleUrlExtraSlash() {
   }
 
   /**
+   * Tests that an invalid source image returns a 404.
+   */
+  function testImageStyleUrlForMissingSourceImage() {
+    $non_existent_uri = 'public://foo.png';
+    $generated_url = image_style_url($this->style_name, $non_existent_uri);
+    $this->drupalGet($generated_url);
+    $this->assertResponse(404, 'Accessing an image style URL with a source image that does not exist provides a 404 error response.');
+  }
+
+  /**
    * Tests image_style_url().
    */
   function _testImageStyleUrlAndPath($scheme, $clean_url = TRUE, $extra_slash = FALSE) {