diff --git a/src/main/java/org/qortal/controller/Synchronizer.java b/src/main/java/org/qortal/controller/Synchronizer.java
index cba5d3c0..6ceee7f3 100644
--- a/src/main/java/org/qortal/controller/Synchronizer.java
+++ b/src/main/java/org/qortal/controller/Synchronizer.java
@@ -970,7 +970,8 @@ public class Synchronizer {
 	private SynchronizationResult applyNewBlocks(Repository repository, BlockData commonBlockData, int ourInitialHeight,
 												 Peer peer, int peerHeight, List<BlockSummaryData> peerBlockSummaries) throws InterruptedException, DataException {
 
-		if (Settings.getInstance().isFastSyncEnabled() && peer.getPeersVersion() >= PEER_VERSION_160)
+		final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
+		if (Settings.getInstance().isFastSyncEnabled() && peer.getPeersVersion() >= PEER_VERSION_160 && ourLatestBlockData.isTrimmed())
 			// This peer supports syncing multiple blocks at once via GetBlocksMessage, and it is enabled in the settings
 			return this.applyNewBlocksUsingFastSync(repository, commonBlockData, ourInitialHeight, peer, peerHeight, peerBlockSummaries);
 		else
diff --git a/src/main/java/org/qortal/data/block/BlockData.java b/src/main/java/org/qortal/data/block/BlockData.java
index 3567d0f8..e2d6bad1 100644
--- a/src/main/java/org/qortal/data/block/BlockData.java
+++ b/src/main/java/org/qortal/data/block/BlockData.java
@@ -9,7 +9,10 @@ import javax.xml.bind.annotation.XmlAccessorType;
 import javax.xml.bind.annotation.XmlElement;
 import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
 
+import org.qortal.block.BlockChain;
+import org.qortal.settings.Settings;
 import org.qortal.crypto.Crypto;
+import org.qortal.utils.NTP;
 
 // All properties to be converted to JSON via JAX-RS
 @XmlAccessorType(XmlAccessType.FIELD)
@@ -204,6 +207,13 @@ public class BlockData implements Serializable {
 		return this.onlineAccountsSignatures;
 	}
 
+	public boolean isTrimmed() {
+		long onlineAccountSignaturesTrimmedTimestamp = NTP.getTime() - BlockChain.getInstance().getOnlineAccountSignaturesMaxLifetime();
+		long currentTrimmableTimestamp = NTP.getTime() - Settings.getInstance().getAtStatesMaxLifetime();
+		long blockTimestamp = this.getTimestamp();
+		return blockTimestamp < onlineAccountSignaturesTrimmedTimestamp && blockTimestamp < currentTrimmableTimestamp;
+	}
+
 	// JAXB special
 
 	@XmlElement(name = "minterAddress")