diff --git a/MagickCore/resize.c b/MagickCore/resize.c
index 50da4efb6c..6ca8626b2b 100644
--- a/MagickCore/resize.c
+++ b/MagickCore/resize.c
@@ -4674,7 +4674,7 @@ MagickExport Image *ThumbnailImage(const Image *image,const size_t columns,
   }
   (void) DeleteImageProperty(thumbnail_image,"comment");
   url_encode(thumbnail_image->magick_filename,uri);
-  if (strstr(thumbnail_image->magick_filename,"//") == (char *) NULL)
+  if (strstr(thumbnail_image->magick_filename,"//") != (char *) NULL)
     (void) FormatImageProperty(thumbnail_image,"Thumb::URI","file://%s",uri);
   else
     (void) FormatImageProperty(thumbnail_image,"Thumb::URI","./%s",uri);