diff --git a/libs/compression/compression.h b/libs/compression/compression.h
index 5076697..f0c12d4 100644
--- a/libs/compression/compression.h
+++ b/libs/compression/compression.h
@@ -3,6 +3,11 @@
 
 #include <QtGlobal>
 
+// Windows calling conventions - define as empty on non-Windows
+#ifndef Q_OS_WIN
+#define __stdcall
+#endif
+
 #ifdef Q_OS_WIN
 #include "QtZlib/zlib.h"
 #else