diff --git a/src/indexing.jl b/src/indexing.jl
index ad89a85..e73633c 100644
--- a/src/indexing.jl
+++ b/src/indexing.jl
@@ -138,7 +138,7 @@ You can also work with it directly, say you wanted to get all checkpoints files
 2: https://github.com/JuliaData/DataFrames.jl
 """
 function index_checkpoint_files(dir::AbstractPath)
-    isdir(dir) || throw(ArgumentError(dir, "Need an existing directory."))
+    isdir(dir) || throw(ArgumentError("Need an existing directory."))
     map(Iterators.filter(==("jlso") ∘ extension, walkpath(dir))) do checkpoint_path
         return IndexEntry(checkpoint_path)
     end
diff --git a/test/indexing.jl b/test/indexing.jl
index 486014f..b224708 100644
--- a/test/indexing.jl
+++ b/test/indexing.jl
@@ -53,4 +53,8 @@
             @test_throws ErrorException entry.tags
         end
     end
+
+    @testset "nonexistent dir" begin
+        @test_throws ArgumentError index_checkpoint_files("nonexistent_dir")
+    end
 end