diff --git a/dlib/image_transforms/draw_abstract.h b/dlib/image_transforms/draw_abstract.h
index 7fe31b2c7..2aad37171 100644
--- a/dlib/image_transforms/draw_abstract.h
+++ b/dlib/image_transforms/draw_abstract.h
@@ -14,7 +14,7 @@ namespace dlib
         typename pixel_type
         >
     void draw_line (
-        image_type& c,
+        image_type& img,
         const point& p1,
         const point& p2,
         const pixel_type& val