diff --git a/p2p/base/connection.h b/p2p/base/connection.h
index 405a1def90..d4232cd59c 100644
--- a/p2p/base/connection.h
+++ b/p2p/base/connection.h
@@ -71,7 +71,7 @@ class ConnectionRequest : public StunRequest {
 
 // Represents a communication link between a port on the local client and a
 // port on the remote client.
-class Connection : public CandidatePairInterface, public sigslot::has_slots<> {
+class Connection : public CandidatePairInterface {
  public:
   struct SentPing {
     SentPing(const std::string id, int64_t sent_time, uint32_t nomination)
diff --git a/p2p/base/stun_request_unittest.cc b/p2p/base/stun_request_unittest.cc
index 226cc95f46..050df0b1b0 100644
--- a/p2p/base/stun_request_unittest.cc
+++ b/p2p/base/stun_request_unittest.cc
@@ -39,7 +39,7 @@ int TotalDelay(int sends) {
 }
 }  // namespace
 
-class StunRequestTest : public ::testing::Test, public sigslot::has_slots<> {
+class StunRequestTest : public ::testing::Test {
  public:
   StunRequestTest()
       : manager_(rtc::Thread::Current(),
diff --git a/p2p/base/tcp_port.h b/p2p/base/tcp_port.h
index daf88f2e3c..6bd935f613 100644
--- a/p2p/base/tcp_port.h
+++ b/p2p/base/tcp_port.h
@@ -124,7 +124,7 @@ class TCPPort : public Port {
   friend class TCPConnection;
 };
 
-class TCPConnection : public Connection {
+class TCPConnection : public Connection, public sigslot::has_slots<> {
  public:
   // Connection is outgoing unless socket is specified
   TCPConnection(rtc::WeakPtr<Port> tcp_port,