diff --git a/kolab_export.h b/kolab_export.h
--- a/kolab_export.h
+++ b/kolab_export.h
@@ -23,8 +23,8 @@
 
 #include <qglobal.h>
 
-//Workaround for qt not defining Q_DECL_IMPORT as it should
-#if defined(Q_OS_LINUX)
+/* Workaround for Qt4 not defining Q_DECL_IMPORT as it should. */
+#if !defined(Q_OS_WIN)
 #  undef Q_DECL_IMPORT
 #  define Q_DECL_IMPORT     __attribute__((visibility("default")))
 #endif
@@ -33,8 +33,8 @@
 # if defined(KOLAB_STATIC_LIBS)
 /* No export/import for static libraries */
 #  define KOLAB_EXPORT
-# elif defined(MAKE_KOLAB_LIB)
-/* We are building this library */
+# elif defined(kolab_EXPORTS)
+/* We are building this library. kolab_EXPORTS is defined by CMake. */
 #  define KOLAB_EXPORT Q_DECL_EXPORT
 # else
 /* We are using this library */