diff --git a/file.lua b/file.lua
index 62b075e..228f1f3 100644
--- a/file.lua
+++ b/file.lua
@@ -37,7 +37,7 @@ end
 
 function save_to_disk(State)
   local outfile = App.open_for_writing(State.filename)
-  if outfile == nil then
+  if not outfile then
     error('failed to write to "'..State.filename..'"')
   end
   for _,line in ipairs(State.lines) do
diff --git a/source_file.lua b/source_file.lua
index b0e26eb..dbb6f95 100644
--- a/source_file.lua
+++ b/source_file.lua
@@ -45,7 +45,7 @@ end
 
 function save_to_disk(State)
   local outfile = App.open_for_writing(App.save_dir..State.filename)
-  if outfile == nil then
+  if not outfile then
     error('failed to write to "'..State.filename..'"')
   end
   for _,line in ipairs(State.lines) do