diff --git a/packages/proto/src/generated/sds_message.ts b/packages/proto/src/generated/sds_message.ts
index 20ef8746ae..f91ef23cfa 100644
--- a/packages/proto/src/generated/sds_message.ts
+++ b/packages/proto/src/generated/sds_message.ts
@@ -117,7 +117,7 @@ export namespace SdsMessage {
 
         if (obj.lamportTimestamp != null) {
           w.uint32(80)
-          w.int32(obj.lamportTimestamp)
+          w.uint32(obj.lamportTimestamp)
         }
 
         if (obj.causalHistory != null) {
@@ -167,7 +167,7 @@ export namespace SdsMessage {
               break
             }
             case 10: {
-              obj.lamportTimestamp = reader.int32()
+              obj.lamportTimestamp = reader.uint32()
               break
             }
             case 11: {
diff --git a/packages/proto/src/lib/sds_message.proto b/packages/proto/src/lib/sds_message.proto
index 5344a0d33a..626ae12525 100644
--- a/packages/proto/src/lib/sds_message.proto
+++ b/packages/proto/src/lib/sds_message.proto
@@ -9,7 +9,7 @@ message SdsMessage {
   string sender_id = 1;           // Participant ID of the message sender
   string message_id = 2;          // Unique identifier of the message
   string channel_id = 3;          // Identifier of the channel to which the message belongs
-  optional int32 lamport_timestamp = 10;    // Logical timestamp for causal ordering in channel
+  optional uint32 lamport_timestamp = 10;    // Logical timestamp for causal ordering in channel
   repeated HistoryEntry causal_history = 11;  // List of preceding message IDs that this message causally depends on. Generally 2 or 3 message IDs are included.
   optional bytes bloom_filter = 12;         // Bloom filter representing received message IDs in channel
   optional bytes content = 20;             // Actual content of the message
diff --git a/packages/sds/src/message_channel/message_channel.ts b/packages/sds/src/message_channel/message_channel.ts
index 6375e819f7..9b1ab0e885 100644
--- a/packages/sds/src/message_channel/message_channel.ts
+++ b/packages/sds/src/message_channel/message_channel.ts
@@ -95,9 +95,8 @@ export class MessageChannel extends TypedEventEmitter<MessageChannelEvents> {
     super();
     this.channelId = channelId;
     this.senderId = senderId;
-    // SDS RFC says to use nanoseconds, but current time in nanosecond is > Number.MAX_SAFE_INTEGER
-    // So instead we are using milliseconds and proposing a spec change (TODO)
-    this.lamportTimestamp = Date.now();
+    // Initialize channel lamport timestamp to current time in seconds.
+    this.lamportTimestamp = Date.now() / 1000;
     this.filter = new DefaultBloomFilter(DEFAULT_BLOOM_FILTER_OPTIONS);
     this.outgoingBuffer = [];
     this.possibleAcks = new Map();