diff --git a/src/s3path.jl b/src/s3path.jl
index b0bee27c..69727f6d 100644
--- a/src/s3path.jl
+++ b/src/s3path.jl
@@ -582,7 +582,7 @@ function Base.readdir(fp::S3Path; join=false, sort=true)
         sort && sort!(results)
 
         # Return results, possibly joined with the root path if join=true
-        return join ? joinpath.(fp, results) : results
+        return join ? string.(joinpath.(fp, results)) : results
     else
         throw(ArgumentError("\"$fp\" is not a directory"))
     end
diff --git a/test/s3path.jl b/test/s3path.jl
index c3f7fa4c..511501a3 100644
--- a/test/s3path.jl
+++ b/test/s3path.jl
@@ -245,17 +245,17 @@ end
 function verify_files(path::S3Path)
     @test readdir(path) == ["emptydir/", "subdir1/", "test_01.txt"]
     @test readdir(path; join=true) ==
-        [path / "emptydir/", path / "subdir1/", path / "test_01.txt"]
+        String[path / "emptydir/", path / "subdir1/", path / "test_01.txt"]
     @test readdir(path / "emptydir/") == []
     @test readdir(path / "emptydir/"; join=true) == []
     @test readdir(path / "subdir1/") == ["subdir2/", "test_02.txt", "test_03.txt"]
-    @test readdir(path / "subdir1/"; join=true) == [
+    @test readdir(path / "subdir1/"; join=true) == String[
         path / "subdir1/" / "subdir2/",
         path / "subdir1/" / "test_02.txt",
         path / "subdir1/" / "test_03.txt",
     ]
     @test readdir(path / "subdir1/subdir2/") == ["subdir3/", "test_04.txt"]
-    @test readdir(path / "subdir1/subdir2/"; join=true) == [
+    @test readdir(path / "subdir1/subdir2/"; join=true) == String[
         path / "subdir1/subdir2/" / "subdir3/", path / "subdir1/subdir2/" / "test_04.txt"
     ]
     @test readdir(path / "subdir1/subdir2/subdir3/") == []
@@ -269,7 +269,7 @@ function verify_files(path::AbstractPath)
     @test readdir(path / "emptydir/") == []
     VERSION >= v"1.4.0" && @test readdir(path / "emptydir/"; join=true) == []
     @test readdir(path / "subdir1/") == ["subdir2", "test_02.txt", "test_03.txt"]
-    VERSION >= v"1.4.0" && @test readdir(path / "subdir1/"; join=true) == [
+    VERSION >= v"1.4.0" && @test readdir(path / "subdir1/"; join=true) == String[
         path / "subdir1" / "subdir2",
         path / "subdir1" / "test_02.txt",
         path / "subdir1/" / "subdir1/test_03.txt",