diff --git a/src/impl/win.cc b/src/impl/win.cc
index 92a5c62..39cc8b2 100644
--- a/src/impl/win.cc
+++ b/src/impl/win.cc
@@ -315,14 +315,14 @@ Serial::SerialImpl::available ()
 }
 
 bool
-Serial::SerialImpl::waitReadable (uint32_t timeout)
+Serial::SerialImpl::waitReadable (uint32_t /*timeout*/)
 {
   THROW (IOException, "waitReadable is not implemented on Windows.");
   return false;
 }
 
 void
-Serial::SerialImpl::waitByteTimes (size_t count)
+Serial::SerialImpl::waitByteTimes (size_t /*count*/)
 {
   THROW (IOException, "waitByteTimes is not implemented on Windows.");
 }
@@ -481,7 +481,7 @@ Serial::SerialImpl::flushOutput ()
 }
 
 void
-Serial::SerialImpl::sendBreak (int duration)
+Serial::SerialImpl::sendBreak (int /*duration*/)
 {
   THROW (IOException, "sendBreak is not supported on Windows.");
 }