diff --git a/dummyimage.module b/dummyimage.module
index add01a0..25c14ba 100644
--- a/dummyimage.module
+++ b/dummyimage.module
@@ -111,7 +111,10 @@ function dummyimage_preprocess_image(&$variables) {
 
   switch (variable_get('dummyimages_generate', DUMMYIMAGE_GENERATE_NONE)) {
     case DUMMYIMAGE_GENERATE_MISSING:
-      if (is_file($variables['path'])) {
+      // Reconstruct the original uri to check if it exist.
+      $path_parts = explode('/', strstr($variables['path'], '/styles/' . $variables['style_name']), 5);
+      $original_uri = $path_parts[3] . '://' . $path_parts[4];
+      if (is_file($original_uri)) {
         break;
       }
     case DUMMYIMAGE_GENERATE_ALL: