diff --git a/blockchain/chainio.go b/blockchain/chainio.go
index 21624159..e510fd5d 100644
--- a/blockchain/chainio.go
+++ b/blockchain/chainio.go
@@ -1905,6 +1905,15 @@ func (b *BlockChain) initThresholdCaches() error {
 			"change.  This might take a while...")
 	}
 
+	// Get the previous block node.  This function is used over simply
+	// accessing b.bestNode.parent directly as it will dynamically create
+	// previous block nodes as needed.  This helps allow only the pieces of
+	// the chain that are needed to remain in memory.
+	prevNode, err := b.getPrevNodeFromNode(b.bestNode)
+	if err != nil {
+		return err
+	}
+
 	// Initialize the warning and deployment caches by calculating the
 	// threshold state for each of them.  This will ensure the caches are
 	// populated and any states that needed to be recalculated due to
@@ -1912,7 +1921,7 @@ func (b *BlockChain) initThresholdCaches() error {
 	for bit := uint32(0); bit < vbNumBits; bit++ {
 		checker := bitConditionChecker{bit: bit, chain: b}
 		cache := &b.warningCaches[bit]
-		_, err := b.thresholdState(b.bestNode, checker, cache)
+		_, err := b.thresholdState(prevNode, checker, cache)
 		if err != nil {
 			return err
 		}
@@ -1921,7 +1930,7 @@ func (b *BlockChain) initThresholdCaches() error {
 		deployment := &b.chainParams.Deployments[id]
 		cache := &b.deploymentCaches[id]
 		checker := deploymentChecker{deployment: deployment, chain: b}
-		_, err := b.thresholdState(b.bestNode, checker, cache)
+		_, err := b.thresholdState(prevNode, checker, cache)
 		if err != nil {
 			return err
 		}
diff --git a/blockchain/thresholdstate.go b/blockchain/thresholdstate.go
index e7620be9..f1ca8d19 100644
--- a/blockchain/thresholdstate.go
+++ b/blockchain/thresholdstate.go
@@ -141,9 +141,9 @@ func newThresholdCaches(numCaches uint32) []thresholdStateCache {
 	return caches
 }
 
-// thresholdState returns the current rule change threshold state for the given
-// node and deployment ID.  The cache is used to ensure the threshold states for
-// previous windows are only calculated once.
+// thresholdState returns the current rule change threshold state for the block
+// AFTER the given node and deployment ID.  The cache is used to ensure the
+// threshold states for previous windows are only calculated once.
 //
 // This function MUST be called with the chain state lock held (for writes).
 func (b *BlockChain) thresholdState(prevNode *blockNode, checker thresholdConditionChecker, cache *thresholdStateCache) (ThresholdState, error) {
@@ -305,7 +305,7 @@ func (b *BlockChain) thresholdState(prevNode *blockNode, checker thresholdCondit
 }
 
 // ThresholdState returns the current rule change threshold state of the given
-// deployment ID for the end of the current best chain.
+// deployment ID for the block AFTER then end of the current best chain.
 //
 // This function is safe for concurrent access.
 func (b *BlockChain) ThresholdState(deploymentID uint32) (ThresholdState, error) {
diff --git a/blockchain/versionbits.go b/blockchain/versionbits.go
index c2ad2cde..4da737d9 100644
--- a/blockchain/versionbits.go
+++ b/blockchain/versionbits.go
@@ -244,12 +244,21 @@ func (b *BlockChain) CalcNextBlockVersion() (int32, error) {
 //
 // This function MUST be called with the chain state lock held (for writes)
 func (b *BlockChain) warnUnknownRuleActivations(node *blockNode) error {
+	// Get the previous block node.  This function is used over simply
+	// accessing node.parent directly as it will dynamically create previous
+	// block nodes as needed.  This helps allow only the pieces of the chain
+	// that are needed to remain in memory.
+	prevNode, err := b.getPrevNodeFromNode(node)
+	if err != nil {
+		return err
+	}
+
 	// Warn if any unknown new rules are either about to activate or have
 	// already been activated.
 	for bit := uint32(0); bit < vbNumBits; bit++ {
 		checker := bitConditionChecker{bit: bit, chain: b}
 		cache := &b.warningCaches[bit]
-		state, err := b.thresholdState(node, checker, cache)
+		state, err := b.thresholdState(prevNode, checker, cache)
 		if err != nil {
 			return err
 		}