diff --git a/xs/src/libslic3r/GUI/GUI.cpp b/xs/src/libslic3r/GUI/GUI.cpp
index 3dec75308..84d5954b4 100644
--- a/xs/src/libslic3r/GUI/GUI.cpp
+++ b/xs/src/libslic3r/GUI/GUI.cpp
@@ -9,7 +9,9 @@
 
 namespace Slic3r { namespace GUI {
 
+#if __APPLE__
 IOPMAssertionID assertionID;
+#endif
 
 void
 disable_screensaver()