Update runtime files
diff --git a/src/gvimtutor b/src/gvimtutor
index c452043..36ca7bc 100644
--- a/src/gvimtutor
+++ b/src/gvimtutor
@@ -5,4 +5,4 @@
 # Usage: gvimtutor [xx]
 # See vimtutor for usage.
 
-exec `dirname $0`/vimtutor -g "$@"
+exec $(dirname $0)/vimtutor -g "$@"