diff --git a/vendor/glpk/env/dlsup.c b/vendor/glpk/env/dlsup.c
index 741354475..968a794b7 100644
--- a/vendor/glpk/env/dlsup.c
+++ b/vendor/glpk/env/dlsup.c
@@ -25,6 +25,8 @@
 
 #include "env.h"
 
+#undef __WOE__
+
 /* GNU version ********************************************************/
 
 #if defined(HAVE_LTDL)