diff --git a/plug.vim b/plug.vim
index 8b14265..c107d49 100644
--- a/plug.vim
+++ b/plug.vim
@@ -713,7 +713,7 @@ function! s:git_valid(spec, check_branch, cd)
       let ret = 0
     elseif a:check_branch
       let branch = result[0]
-      let tag = a:spec.branch == 'master' ? '' :
+      let tag = a:spec.branch ==# 'master' ? '' :
             \ s:system_chomp('git describe --exact-match --tags HEAD 2>&1')
       if a:spec.branch != branch && a:spec.branch != tag
         let msg = 'Invalid branch/tag: ' .