diff --git a/src/add-ons/mail_daemon/outbound_protocols/smtp/smtp.cpp b/src/add-ons/mail_daemon/outbound_protocols/smtp/smtp.cpp
index f3341aefa7..c13b8048e2 100644
--- a/src/add-ons/mail_daemon/outbound_protocols/smtp/smtp.cpp
+++ b/src/add-ons/mail_daemon/outbound_protocols/smtp/smtp.cpp
@@ -964,7 +964,7 @@ SMTPProtocol::ReceiveResponse(BString &out)
             result = 1;
         else
 #endif
-            result = select(1, &fds, NULL, NULL, &tv);
+            result = select(1 + fSocket, &fds, NULL, NULL, &tv);
 	if (result < 0)
 		return errno;