diff --git a/plugin/vimwiki.vim b/plugin/vimwiki.vim
index bdacb3f..766b001 100644
--- a/plugin/vimwiki.vim
+++ b/plugin/vimwiki.vim
@@ -11,7 +11,7 @@ endif
 let g:loaded_vimwiki = 1
 
 " Set to version number for release, otherwise -1 for dev-branch
-let s:plugin_vers = str2float("-1")
+let s:plugin_vers = str2float('-1')
 
 " Get the directory the script is installed in
 let s:plugin_dir = expand('<sfile>:p:h:h')