diff --git a/oximetry.cpp b/oximetry.cpp
index 9b492fa6..4f8bff6c 100644
--- a/oximetry.cpp
+++ b/oximetry.cpp
@@ -939,7 +939,7 @@ void Oximetry::on_RefreshPortsButton_clicked()
     bool current_found=false;
 
     // Windows build mixes these up
-#ifdef Q_WS_WIN32 || Q_WS_MAC
+#if defined(Q_WS_WIN32) || defined(Q_WS_MAC)
 #define qesPORTNAME portName
 #else
 #define qesPORTNAME physName