diff --git a/adm_local/unix/config_files/check_Netgen.m4 b/adm_local/unix/config_files/check_Netgen.m4
index 680870f11..c2dbcb986 100644
--- a/adm_local/unix/config_files/check_Netgen.m4
+++ b/adm_local/unix/config_files/check_Netgen.m4
@@ -112,6 +112,8 @@ else
   AC_MSG_RESULT(yes)
   NETGEN_LIBS="-lNETGEN"
   CPPFLAGS="${CPPFLAGS} -DHAVE_NETGEN"
+  IDLCXXFLAGS="${IDLCXXFLAGS} -DHAVE_NETGEN"
+  IDLPYFLAGS="${IDLPYFLAGS} -DHAVE_NETGEN"
 fi
 fi
 AC_SUBST(NETGEN_INCLUDES)