diff --git a/p2p/base/turn_port.h b/p2p/base/turn_port.h
index 3a7915274a..349190b4ae 100644
--- a/p2p/base/turn_port.h
+++ b/p2p/base/turn_port.h
@@ -66,6 +66,8 @@ class TurnPort : public Port {
       webrtc::TurnCustomizer* customizer) {
     // Do basic parameter validation.
     if (credentials.username.size() > kMaxTurnUsernameLength) {
+      RTC_LOG(LS_ERROR) << "Attempt to use TURN with a too long username "
+                        << "of length " << credentials.username.size();
       return nullptr;
     }
     // Do not connect to low-numbered ports. The default STUN port is 3478.
@@ -117,6 +119,8 @@ class TurnPort : public Port {
       rtc::SSLCertificateVerifier* tls_cert_verifier = nullptr) {
     // Do basic parameter validation.
     if (credentials.username.size() > kMaxTurnUsernameLength) {
+      RTC_LOG(LS_ERROR) << "Attempt to use TURN with a too long username "
+                        << "of length " << credentials.username.size();
       return nullptr;
     }
     // Do not connect to low-numbered ports. The default STUN port is 3478.