diff --git a/nimbus/common/common.nim b/nimbus/common/common.nim
index 7bc86bf51..a7a0a5ec5 100644
--- a/nimbus/common/common.nim
+++ b/nimbus/common/common.nim
@@ -429,6 +429,9 @@ func daoForkSupport*(com: CommonRef): bool =
 func ttd*(com: CommonRef): Option[DifficultyInt] =
   com.config.terminalTotalDifficulty
 
+func ttdPassed*(com: CommonRef): bool =
+  com.config.terminalTotalDifficultyPassed.get(false)
+
 # if you messing with clique period and
 # and epoch, it likely will fail clique verification
 # at epoch * blocknumber
diff --git a/nimbus/sync/beacon/skeleton_main.nim b/nimbus/sync/beacon/skeleton_main.nim
index 2dc8eaf8a..51865b098 100644
--- a/nimbus/sync/beacon/skeleton_main.nim
+++ b/nimbus/sync/beacon/skeleton_main.nim
@@ -49,8 +49,8 @@ proc new*(_: type SkeletonRef, chain: ChainRef): SkeletonRef =
 # ------------------------------------------------------------------------------
 
 proc open*(sk: SkeletonRef): Result[void, string]  =
-  if sk.chain.com.ttd.isNone:
-    return err("Cannot create skeleton as ttd not set")
+  if sk.chain.com.ttd.isNone and sk.chain.com.ttdPassed.not:
+    return err("Cannot create skeleton as ttd and ttdPassed not set")
   sk.readProgress().isOkOr:
     return err(error)
   sk.started = getTime()
diff --git a/tests/test_beacon/test_skeleton.nim b/tests/test_beacon/test_skeleton.nim
index b6e0b8fd3..16c557026 100644
--- a/tests/test_beacon/test_skeleton.nim
+++ b/tests/test_beacon/test_skeleton.nim
@@ -21,7 +21,28 @@ import
   ../../nimbus/sync/beacon/skeleton_main,
   ./setup_env
 
-proc ccm(cc: NetworkParams) =
+proc noTtdAndNoTtdPassed(cc: NetworkParams) =
+  cc.config.terminalTotalDifficultyPassed = none(bool)
+  cc.config.terminalTotalDifficulty = none(UInt256)
+  cc.genesis.difficulty = 1.u256
+
+proc ttdPassedNoTtd(cc: NetworkParams) =
+  cc.config.terminalTotalDifficultyPassed = some(true)
+  cc.config.terminalTotalDifficulty = none(UInt256)
+  cc.genesis.difficulty = 1.u256
+
+proc ttdNoTtdPassed(cc: NetworkParams) =
+  cc.config.terminalTotalDifficultyPassed = none(bool)
+  cc.config.terminalTotalDifficulty = some(0.u256)
+  cc.genesis.difficulty = 1.u256
+
+proc ttdAndTtdPassed(cc: NetworkParams) =
+  cc.config.terminalTotalDifficultyPassed = some(true)
+  cc.config.terminalTotalDifficulty = some(0.u256)
+  cc.genesis.difficulty = 1.u256
+
+proc ttdPassedFalseNoTtd(cc: NetworkParams) =
+  cc.config.terminalTotalDifficultyPassed = some(false)
   cc.config.terminalTotalDifficulty = none(UInt256)
   cc.genesis.difficulty = 1.u256
 
@@ -35,11 +56,34 @@ proc skeletonMain*() =
   test7()
   test8()
 
-  suite "skeleton open should error if ttd not set":
-    let env = setupEnv(extraValidation = true, ccm)
-    let skel = SkeletonRef.new(env.chain)
+  suite "test skeleton open":
+    test "skeleton open should error if both ttd and ttdPassed not set":
+      let env = setupEnv(extraValidation = true, noTtdAndNoTtdPassed)
+      let skel = SkeletonRef.new(env.chain)
+      let res = skel.open()
+      check res.isErr
 
-    test "skel open error":
+    test "skeleton open should ok if ttdPassed is set":
+      let env = setupEnv(extraValidation = true, ttdPassedNoTtd)
+      let skel = SkeletonRef.new(env.chain)
+      let res = skel.open()
+      check res.isOk
+
+    test "skeleton open should ok if ttd is set":
+      let env = setupEnv(extraValidation = true, ttdNoTtdPassed)
+      let skel = SkeletonRef.new(env.chain)
+      let res = skel.open()
+      check res.isOk
+
+    test "skeleton open should ok if both ttd and ttdPassed are set":
+      let env = setupEnv(extraValidation = true, ttdAndTtdPassed)
+      let skel = SkeletonRef.new(env.chain)
+      let res = skel.open()
+      check res.isOk
+
+    test "skeleton open should error if ttd not set and ttdPassed are false":
+      let env = setupEnv(extraValidation = true, ttdPassedFalseNoTtd)
+      let skel = SkeletonRef.new(env.chain)
       let res = skel.open()
       check res.isErr