diff --git a/core/Discover.proto b/core/Discover.proto
index f6bf68cdc33..31797f7acfc 100644
--- a/core/Discover.proto
+++ b/core/Discover.proto
@@ -54,18 +54,18 @@ message PingMessage {
   int32 version = 1;
   Endpoint from = 2;
   Endpoint to = 3;
-  int32 timestamp = 4;
+  int64 timestamp = 4;
 }
 
 message PongMessage {
   Endpoint to = 1;
   int32 echo = 2;
-  int32 timestamp = 3;
+  int64 timestamp = 3;
 }
 
 message FindNeighbours {
   bytes target = 1;
-  int32 timestamp = 2;
+  int64 timestamp = 2;
 }
 
 message Neighbour {
@@ -75,5 +75,5 @@ message Neighbour {
 
 message Neighbours {
   repeated Neighbour neighbours = 1;
-  int32 timestamp = 2;
+  int64 timestamp = 2;
 }
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