diff --git a/src/plugins/projectexplorer/projectmacro.cpp b/src/plugins/projectexplorer/projectmacro.cpp
index cdbd48772e7c19edd572cca5fb18bd0f6dea241f..63f69b6986fc61e4c31eabd763da9650bd0d7f0d 100644
--- a/src/plugins/projectexplorer/projectmacro.cpp
+++ b/src/plugins/projectexplorer/projectmacro.cpp
@@ -109,6 +109,8 @@ QByteArray Macro::toKeyValue(const QByteArray &prefix) const
         keyValue = prefix;
 
     if (value.isEmpty())
+        keyValue += key + '=';
+    else if (value == "1")
         keyValue += key;
     else
         keyValue += key + '=' + value;