diff --git a/api/api_full.go b/api/api_full.go
index 7a477a874..034e8f996 100644
--- a/api/api_full.go
+++ b/api/api_full.go
@@ -164,6 +164,9 @@ type FullNode interface {
 	// Use with extreme caution.
 	SyncMarkBad(ctx context.Context, bcid cid.Cid) error
 
+	// SyncUnmarkBad unmarks a blocks as bad, making it possible to be validated and synced again.
+	SyncUnmarkBad(ctx context.Context, bcid cid.Cid) error
+
 	// SyncCheckBad checks if a block was marked as bad, and if it was, returns
 	// the reason.
 	SyncCheckBad(ctx context.Context, bcid cid.Cid) (string, error)
diff --git a/api/apistruct/struct.go b/api/apistruct/struct.go
index bfd99ab0f..6361e60b3 100644
--- a/api/apistruct/struct.go
+++ b/api/apistruct/struct.go
@@ -107,6 +107,7 @@ type FullNodeStruct struct {
 		SyncIncomingBlocks func(ctx context.Context) (<-chan *types.BlockHeader, error) `perm:"read"`
 		SyncCheckpoint     func(ctx context.Context, key types.TipSetKey) error         `perm:"admin"`
 		SyncMarkBad        func(ctx context.Context, bcid cid.Cid) error                `perm:"admin"`
+		SyncUnmarkBad      func(ctx context.Context, bcid cid.Cid) error                `perm:"admin"`
 		SyncCheckBad       func(ctx context.Context, bcid cid.Cid) (string, error)      `perm:"read"`
 
 		MpoolGetConfig func(context.Context) (*types.MpoolConfig, error) `perm:"read"`
@@ -713,6 +714,10 @@ func (c *FullNodeStruct) SyncMarkBad(ctx context.Context, bcid cid.Cid) error {
 	return c.Internal.SyncMarkBad(ctx, bcid)
 }
 
+func (c *FullNodeStruct) SyncUnmarkBad(ctx context.Context, bcid cid.Cid) error {
+	return c.Internal.SyncUnmarkBad(ctx, bcid)
+}
+
 func (c *FullNodeStruct) SyncCheckBad(ctx context.Context, bcid cid.Cid) (string, error) {
 	return c.Internal.SyncCheckBad(ctx, bcid)
 }
diff --git a/chain/badtscache.go b/chain/badtscache.go
index 103237307..3c5bf05ef 100644
--- a/chain/badtscache.go
+++ b/chain/badtscache.go
@@ -56,6 +56,10 @@ func (bts *BadBlockCache) Add(c cid.Cid, bbr BadBlockReason) {
 	bts.badBlocks.Add(c, bbr)
 }
 
+func (bts *BadBlockCache) Remove(c cid.Cid) {
+	bts.badBlocks.Remove(c)
+}
+
 func (bts *BadBlockCache) Has(c cid.Cid) (BadBlockReason, bool) {
 	rval, ok := bts.badBlocks.Get(c)
 	if !ok {
diff --git a/chain/sync.go b/chain/sync.go
index 47c8c55c9..ccc97e12f 100644
--- a/chain/sync.go
+++ b/chain/sync.go
@@ -1680,6 +1680,11 @@ func (syncer *Syncer) MarkBad(blk cid.Cid) {
 	syncer.bad.Add(blk, NewBadBlockReason([]cid.Cid{blk}, "manually marked bad"))
 }
 
+// UnmarkBad manually adds a block to the "bad blocks" cache.
+func (syncer *Syncer) UnmarkBad(blk cid.Cid) {
+	syncer.bad.Remove(blk)
+}
+
 func (syncer *Syncer) CheckBadBlockCache(blk cid.Cid) (string, bool) {
 	bbr, ok := syncer.bad.Has(blk)
 	return bbr.String(), ok
diff --git a/node/impl/full/sync.go b/node/impl/full/sync.go
index 9fe73220e..7f7fd48be 100644
--- a/node/impl/full/sync.go
+++ b/node/impl/full/sync.go
@@ -108,6 +108,12 @@ func (a *SyncAPI) SyncMarkBad(ctx context.Context, bcid cid.Cid) error {
 	return nil
 }
 
+func (a *SyncAPI) SyncUnmarkBad(ctx context.Context, bcid cid.Cid) error {
+	log.Warnf("Unmarking block %s as bad", bcid)
+	a.Syncer.UnmarkBad(bcid)
+	return nil
+}
+
 func (a *SyncAPI) SyncCheckBad(ctx context.Context, bcid cid.Cid) (string, error) {
 	reason, ok := a.Syncer.CheckBadBlockCache(bcid)
 	if !ok {