Index: libsigc++-2.2.4/sigc++/CMakeLists.txt
===================================================================
--- libsigc++-2.2.4/sigc++/CMakeLists.txt	(revision 3647)
+++ libsigc++-2.2.4/sigc++/CMakeLists.txt	(working copy)
@@ -25,6 +25,10 @@
 set( VERSION 2 )
 set( FULL_VERSION ${VERSION}.0.18 )
 
+if( WINDOWS )
+	add_definitions( -DSIGC_BUILD )
+endif( WINDOWS )
+
 set( SOURCE_FILES
 	trackable.cc
 	connection.cc
