diff --git a/src/dot_env_ffi.erl b/src/dot_env_ffi.erl
index fd8e8a0..1d5f58a 100644
--- a/src/dot_env_ffi.erl
+++ b/src/dot_env_ffi.erl
@@ -5,7 +5,7 @@
 get_env(Name) ->
   case os:getenv(binary_to_list(Name)) of
     false ->
-      {error, nil};
+      {error, list_to_binary(io_lib:format("key ~s is not set", [Name]))};
     Value ->
       {ok, list_to_binary(Value)}
   end.
diff --git a/test/dot_env_test.gleam b/test/dot_env_test.gleam
index 132b862..002f6e7 100644
--- a/test/dot_env_test.gleam
+++ b/test/dot_env_test.gleam
@@ -159,6 +159,9 @@ pub fn load_normal_test() {
 
   env.get("SPACED_KEY")
   |> should.equal(Ok("parsed"))
+
+  env.get("DOESNT_EXIST")
+  |> should.equal(Error("key DOESNT_EXIST is not set"))
 }
 
 pub fn load_multiline_test() {