diff --git a/persist/filesystem.go b/persist/filesystem.go
index a6b9abe..af8c251 100644
--- a/persist/filesystem.go
+++ b/persist/filesystem.go
@@ -5,13 +5,10 @@ import (
 	"os"
 	"path/filepath"
 	"time"
-
-	"github.com/spf13/afero"
 )
 
 // FsStore is a Store that uses the filesystem to store cache data
 type FsStore struct {
-	afs        afero.Fs
 	dir        string
 	useSafeKey bool
 }
@@ -19,7 +16,6 @@ type FsStore struct {
 // NewFsStore creates a new FsStore, dir is the rood directory where all cached files will be stored
 func NewFsStore(dir string, useSafeKey bool) *FsStore {
 	return &FsStore{
-		afs:        afero.NewOsFs(),
 		dir:        dir,
 		useSafeKey: useSafeKey,
 	}
@@ -40,7 +36,7 @@ func (c *FsStore) Get(_ context.Context, key string) ([]byte, time.Time, error)
 		return nil, time.Time{}, err
 	}
 
-	raw, err := afero.ReadFile(c.afs, file)
+	raw, err := os.ReadFile(file)
 	if err != nil {
 		return nil, time.Time{}, err
 	}
@@ -51,8 +47,8 @@ func (c *FsStore) Get(_ context.Context, key string) ([]byte, time.Time, error)
 // Set writes or updates a file that matches the provided key in the stores root directory. The file will contain
 // the raw bytes passed in by val
 func (c *FsStore) Set(_ context.Context, key string, val []byte) error {
-	if _, err := c.afs.Stat(c.dir); os.IsNotExist(err) {
-		err := c.afs.MkdirAll(c.dir, 0750)
+	if _, err := os.Stat(c.dir); os.IsNotExist(err) {
+		err := os.MkdirAll(c.dir, 0750)
 		if err != nil {
 			return err
 		}
@@ -62,7 +58,7 @@ func (c *FsStore) Set(_ context.Context, key string, val []byte) error {
 		key = SafeKey(key)
 	}
 	file := filepath.Join(c.dir, key)
-	err := afero.WriteFile(c.afs, file, val, 0666)
+	err := os.WriteFile(file, val, 0666)
 	if err != nil {
 		return err
 	}
diff --git a/persist/filesystem_test.go b/persist/filesystem_test.go
new file mode 100644
index 0000000..6dfec9a
--- /dev/null
+++ b/persist/filesystem_test.go
@@ -0,0 +1,206 @@
+package persist
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"reflect"
+	"testing"
+	"time"
+)
+
+func TestFsStore_Get(t *testing.T) {
+	type fields struct {
+		dir        string
+		useSafeKey bool
+	}
+	type args struct {
+		ctx context.Context
+		key string
+	}
+	tests := []struct {
+		name      string
+		fields    fields
+		args      args
+		wantBytes []byte
+		wantTS    time.Time
+		wantErr   bool
+	}{
+		{
+			"use safe key",
+			fields{
+				dir: func() string {
+					dir := t.TempDir()
+					err := os.WriteFile(filepath.Join(dir, SafeKey("safe_key")), []byte(`test`), 0o0644)
+					if err != nil {
+						t.Error("failed to write test file", err)
+					}
+
+					return dir
+				}(),
+				useSafeKey: true,
+			},
+			args{
+				ctx: context.Background(),
+				key: "safe_key",
+			},
+			[]byte(`test`),
+			time.Now(),
+			false,
+		},
+		{
+			"file does not exist",
+			fields{
+				dir:        t.TempDir(),
+				useSafeKey: false,
+			},
+			args{
+				ctx: context.Background(),
+				key: "test_key",
+			},
+			nil,
+			time.Time{},
+			false,
+		},
+		{
+			"permission error",
+			fields{
+				dir: func() string {
+					dir := t.TempDir()
+					err := os.WriteFile(filepath.Join(dir, "test_key"), []byte(`test`), 0o0222)
+					if err != nil {
+						t.Error("failed to write test file", err)
+					}
+					return dir
+				}(),
+			},
+			args{
+				ctx: context.Background(),
+				key: "test_key",
+			},
+			nil,
+			time.Time{},
+			true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			c := &FsStore{
+				dir:        tt.fields.dir,
+				useSafeKey: tt.fields.useSafeKey,
+			}
+			gotBytes, gotTS, err := c.Get(tt.args.ctx, tt.args.key)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("FsStore.Get() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !reflect.DeepEqual(gotBytes, tt.wantBytes) {
+				t.Errorf("FsStore.Get() gotBytes = %v, want %v", gotBytes, tt.wantBytes)
+			}
+
+			// use a range so time stamps dont have to match exactly
+			if tt.wantTS.Before(gotTS.Add(-time.Millisecond*10)) ||
+				tt.wantTS.After(gotTS.Add(time.Millisecond*10)) {
+				t.Errorf("FsStore.Get() gotTS = %v, want %v", gotTS, tt.wantTS)
+			}
+		})
+	}
+}
+
+func TestFsStore_Set(t *testing.T) {
+	type fields struct {
+		dir        string
+		useSafeKey bool
+	}
+	type args struct {
+		ctx context.Context
+		key string
+		val []byte
+	}
+	tests := []struct {
+		name     string
+		fields   fields
+		args     args
+		wantFile []byte
+		wantErr  bool
+	}{
+		{
+			"dir does not exist",
+			fields{
+				dir:        filepath.Join(t.TempDir(), "nested"),
+				useSafeKey: false,
+			},
+			args{
+				ctx: context.Background(),
+				key: "test_key",
+				val: []byte(`test`),
+			},
+			[]byte(`test`),
+			false,
+		},
+		{
+			"use safe key",
+			fields{
+				dir:        t.TempDir(),
+				useSafeKey: true,
+			},
+			args{
+				ctx: context.Background(),
+				key: "safe_key",
+				val: []byte(`test`),
+			},
+			[]byte(`test`),
+			false,
+		},
+		{
+			"permission denyed",
+			fields{
+				dir: func() string {
+					dir := t.TempDir()
+					err := os.Chmod(dir, 0o0666)
+					if err != nil {
+						t.Error("FsStore.Set() failed to set up dir", err)
+					}
+
+					return dir
+				}(),
+				useSafeKey: false,
+			},
+			args{
+				ctx: context.Background(),
+				key: "test_key",
+				val: []byte(`test`),
+			},
+			nil,
+			true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			c := &FsStore{
+				dir:        tt.fields.dir,
+				useSafeKey: tt.fields.useSafeKey,
+			}
+			if err := c.Set(tt.args.ctx, tt.args.key, tt.args.val); (err != nil) != tt.wantErr {
+				t.Errorf("FsStore.Set() error = %v, wantErr %v", err, tt.wantErr)
+			}
+			if tt.wantErr {
+				return
+			}
+
+			// check the file was written
+			key := tt.args.key
+			if c.useSafeKey {
+				key = SafeKey(key)
+			}
+
+			got, err := os.ReadFile(filepath.Join(c.dir, key))
+			if err != nil {
+				t.Error("FsStore.Set() failed to read cache file", err)
+			}
+			if !reflect.DeepEqual(got, tt.wantFile) {
+				t.Errorf("FsStore.Set() cache file = %s, wanted = %s", string(got), string(tt.wantFile))
+			}
+		})
+	}
+}