diff --git a/node/config/load.go b/node/config/load.go
index 1590efedb..b0786643f 100644
--- a/node/config/load.go
+++ b/node/config/load.go
@@ -12,7 +12,7 @@ import (
 )
 
 // FromFile loads config from a specified file overriding defaults specified in
-// the def parameter. If file does not exist or is empty defaults are asummed.
+// the def parameter. If file does not exist or is empty defaults are assumed.
 func FromFile(path string, def interface{}) (interface{}, error) {
 	file, err := os.Open(path)
 	switch {
diff --git a/node/repo/fsrepo.go b/node/repo/fsrepo.go
index 6733b0868..b223731d9 100644
--- a/node/repo/fsrepo.go
+++ b/node/repo/fsrepo.go
@@ -11,6 +11,7 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/BurntSushi/toml"
 	"github.com/ipfs/go-datastore"
 	fslock "github.com/ipfs/go-fs-lock"
 	logging "github.com/ipfs/go-log/v2"
@@ -229,6 +230,7 @@ type fsLockedRepo struct {
 	dsOnce sync.Once
 
 	storageLk sync.Mutex
+	configLk  sync.Mutex
 }
 
 func (fsr *fsLockedRepo) Path() string {
@@ -265,12 +267,50 @@ func (fsr *fsLockedRepo) stillValid() error {
 }
 
 func (fsr *fsLockedRepo) Config() (interface{}, error) {
-	if err := fsr.stillValid(); err != nil {
-		return nil, err
-	}
+	fsr.configLk.Lock()
+	defer fsr.configLk.Unlock()
+
+	return fsr.loadConfigFromDisk()
+}
+
+func (fsr *fsLockedRepo) loadConfigFromDisk() (interface{}, error) {
 	return config.FromFile(fsr.join(fsConfig), defConfForType(fsr.repoType))
 }
 
+func (fsr *fsLockedRepo) SetConfig(c func(interface{})) error {
+	if err := fsr.stillValid(); err != nil {
+		return err
+	}
+
+	fsr.configLk.Lock()
+	defer fsr.configLk.Unlock()
+
+	cfg, err := fsr.loadConfigFromDisk()
+	if err != nil {
+		return err
+	}
+
+	// mutate in-memory representation of config
+	c(cfg)
+
+	// buffer into which we write TOML bytes
+	buf := new(bytes.Buffer)
+
+	// encode now-mutated config as TOML and write to buffer
+	err = toml.NewEncoder(buf).Encode(cfg)
+	if err != nil {
+		return err
+	}
+
+	// write buffer of TOML bytes to config file
+	err = ioutil.WriteFile(fsr.join(fsConfig), buf.Bytes(), 0644)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
 func (fsr *fsLockedRepo) GetStorage() (stores.StorageConfig, error) {
 	fsr.storageLk.Lock()
 	defer fsr.storageLk.Unlock()
diff --git a/node/repo/interface.go b/node/repo/interface.go
index d81d644c7..5950f813f 100644
--- a/node/repo/interface.go
+++ b/node/repo/interface.go
@@ -38,6 +38,7 @@ type LockedRepo interface {
 
 	// Returns config in this repo
 	Config() (interface{}, error)
+	SetConfig(func(interface{})) error
 
 	GetStorage() (stores.StorageConfig, error)
 	SetStorage(func(*stores.StorageConfig)) error
diff --git a/node/repo/memrepo.go b/node/repo/memrepo.go
index 17eeb0253..399b239c1 100644
--- a/node/repo/memrepo.go
+++ b/node/repo/memrepo.go
@@ -30,8 +30,16 @@ type MemRepo struct {
 	token    *byte
 
 	datastore datastore.Datastore
-	configF   func(t RepoType) interface{}
 	keystore  map[string]types.KeyInfo
+
+	// given a repo type, produce the default config
+	configF func(t RepoType) interface{}
+
+	// holds the current config value
+	config struct {
+		sync.Mutex
+		val interface{}
+	}
 }
 
 type lockedMemRepo struct {
@@ -45,6 +53,10 @@ type lockedMemRepo struct {
 }
 
 func (lmem *lockedMemRepo) GetStorage() (stores.StorageConfig, error) {
+	if err := lmem.checkToken(); err != nil {
+		return stores.StorageConfig{}, err
+	}
+
 	if lmem.sc == nil {
 		lmem.sc = &stores.StorageConfig{StoragePaths: []stores.LocalPath{
 			{Path: lmem.Path()},
@@ -55,6 +67,10 @@ func (lmem *lockedMemRepo) GetStorage() (stores.StorageConfig, error) {
 }
 
 func (lmem *lockedMemRepo) SetStorage(c func(*stores.StorageConfig)) error {
+	if err := lmem.checkToken(); err != nil {
+		return err
+	}
+
 	_, _ = lmem.GetStorage()
 
 	c(lmem.sc)
@@ -221,11 +237,32 @@ func (lmem *lockedMemRepo) Config() (interface{}, error) {
 	if err := lmem.checkToken(); err != nil {
 		return nil, err
 	}
-	return lmem.mem.configF(lmem.t), nil
+
+	lmem.mem.config.Lock()
+	defer lmem.mem.config.Unlock()
+
+	if lmem.mem.config.val == nil {
+		lmem.mem.config.val = lmem.mem.configF(lmem.t)
+	}
+
+	return lmem.mem.config.val, nil
 }
 
-func (lmem *lockedMemRepo) Storage() (stores.StorageConfig, error) {
-	panic("implement me")
+func (lmem *lockedMemRepo) SetConfig(c func(interface{})) error {
+	if err := lmem.checkToken(); err != nil {
+		return err
+	}
+
+	lmem.mem.config.Lock()
+	defer lmem.mem.config.Unlock()
+
+	if lmem.mem.config.val == nil {
+		lmem.mem.config.val = lmem.mem.configF(lmem.t)
+	}
+
+	c(lmem.mem.config.val)
+
+	return nil
 }
 
 func (lmem *lockedMemRepo) SetAPIEndpoint(ma multiaddr.Multiaddr) error {
diff --git a/node/repo/repo_test.go b/node/repo/repo_test.go
index 9c43e8f4b..444fab267 100644
--- a/node/repo/repo_test.go
+++ b/node/repo/repo_test.go
@@ -9,6 +9,8 @@ import (
 
 	"github.com/filecoin-project/lotus/chain/types"
 	"github.com/filecoin-project/lotus/node/config"
+
+	"github.com/stretchr/testify/require"
 )
 
 func basicTest(t *testing.T, repo Repo) {
@@ -47,10 +49,23 @@ func basicTest(t *testing.T, repo Repo) {
 	assert.NoError(t, err, "setting multiaddr shouldn't error")
 	assert.Equal(t, ma, apima, "returned API multiaddr should be the same")
 
-	cfg, err := lrepo.Config()
-	assert.Equal(t, config.DefaultFullNode(), cfg, "there should be a default config")
+	c1, err := lrepo.Config()
+	assert.Equal(t, config.DefaultFullNode(), c1, "there should be a default config")
 	assert.NoError(t, err, "config should not error")
 
+	// mutate config and persist back to repo
+	err = lrepo.SetConfig(func(c interface{}) {
+		cfg := c.(*config.FullNode)
+		cfg.Client.IpfsMAddr = "duvall"
+	})
+	assert.NoError(t, err)
+
+	// load config and verify changes
+	c2, err := lrepo.Config()
+	require.NoError(t, err)
+	cfg2 := c2.(*config.FullNode)
+	require.Equal(t, cfg2.Client.IpfsMAddr, "duvall")
+
 	err = lrepo.Close()
 	assert.NoError(t, err, "should be able to close")