diff --git a/win/configure.ac b/win/configure.ac
index b3c4e47..256d69a 100644
--- a/win/configure.ac
+++ b/win/configure.ac
@@ -21,6 +21,7 @@
 fi
 
 CPPFLAGS="$CPPFLAGS -DWINVER=0x0500 -D_WIN32_IE=0x0500"
+CXXFLAGS="$CXXFLAGS -mthreads"
 
 AC_PATH_XTRA