diff --git a/lemon/glpk.cc b/lemon/glpk.cc
--- a/lemon/glpk.cc
+++ b/lemon/glpk.cc
@@ -526,6 +526,8 @@
     glp_free_env();
   }
 
+  GlpkBase::FreeEnvHelper GlpkBase::freeEnvHelper;
+
   // GlpkLp members
 
   GlpkLp::GlpkLp()