diff --git a/p2p/base/turn_port.cc b/p2p/base/turn_port.cc
index 18a84d02ee..6c2110a873 100644
--- a/p2p/base/turn_port.cc
+++ b/p2p/base/turn_port.cc
@@ -312,6 +312,20 @@ TurnPort::~TurnPort() {
   }
 }
 
+void TurnPort::set_realm(absl::string_view realm) {
+  if (realm.empty()) {
+    // Fail silently since this reduces the entropy going into the hash but log
+    // a warning.
+    RTC_LOG(LS_WARNING) << "Setting realm to the empty string, "
+                        << "this is not supported.";
+    return;
+  }
+  if (realm != realm_) {
+    realm_ = std::string(realm);
+    UpdateHash();
+  }
+}
+
 rtc::SocketAddress TurnPort::GetLocalAddress() const {
   return socket_ ? socket_->GetLocalAddress() : rtc::SocketAddress();
 }
diff --git a/p2p/base/turn_port.h b/p2p/base/turn_port.h
index 099d8b258a..69832aef7f 100644
--- a/p2p/base/turn_port.h
+++ b/p2p/base/turn_port.h
@@ -252,12 +252,7 @@ class TurnPort : public Port {
   bool CreateTurnClientSocket();
 
   void set_nonce(absl::string_view nonce) { nonce_ = std::string(nonce); }
-  void set_realm(absl::string_view realm) {
-    if (realm != realm_) {
-      realm_ = std::string(realm);
-      UpdateHash();
-    }
-  }
+  void set_realm(absl::string_view realm);
 
   void OnRefreshError();
   void HandleRefreshError();