diff --git a/lua/nvim-tree/view.lua b/lua/nvim-tree/view.lua
index 0d956db4..94d4d43c 100644
--- a/lua/nvim-tree/view.lua
+++ b/lua/nvim-tree/view.lua
@@ -253,6 +253,8 @@ local function get_size()
   local size = M.View[width_or_height]
   if type(size) == "number" then
     return size
+  elseif type(size) == "function" then
+    return size()
   end
   local size_as_number = tonumber(size:sub(0, -2))
   local percent_as_decimal = size_as_number / 100