diff --git a/CallsignValidator.cpp b/CallsignValidator.cpp
index 02771a4..671f968 100644
--- a/CallsignValidator.cpp
+++ b/CallsignValidator.cpp
@@ -10,7 +10,7 @@ auto CallsignValidator::validate (QString& input, int& pos) const -> State
 {
   auto match = re_.match (input, 0, QRegularExpression::PartialPreferCompleteMatch);
   input = input.toUpper ();
-  if (input.count(QLatin1Char('/')) > 1) return Invalid;
+  if (input.count(QLatin1Char('/')) > 2) return Invalid;
   if (match.hasMatch ()) return Acceptable;
   if (!input.size () || match.hasPartialMatch ()) return Intermediate;
   pos = input.size ();
diff --git a/js8call.pro b/js8call.pro
index aee517d..1dcc7be 100644
--- a/js8call.pro
+++ b/js8call.pro
@@ -85,7 +85,8 @@ SOURCES += \
     SpotClient.cpp \
     TCPClient.cpp \
     TransmitTextEdit.cpp \
-    NotificationAudio.cpp
+    NotificationAudio.cpp \
+    CallsignValidator.cpp
 
 HEADERS  += qt_helpers.hpp \
   pimpl_h.hpp pimpl_impl.hpp \