diff --git a/libwhisper/Common.h b/libwhisper/Common.h
index c05ac34ca..7a0707801 100644
--- a/libwhisper/Common.h
+++ b/libwhisper/Common.h
@@ -58,8 +58,8 @@ enum WhisperPacket
 	PacketCount
 };
 
-const int TopicBloomFilterSize = 64;
-const int WhisperProtocolVersion = 3;
+static const int TopicBloomFilterSize = 64;
+static const int WhisperProtocolVersion = 3;
 
 using AbridgedTopic = FixedHash<4>;
 using Topic = h256;