diff --git a/src/smt/theory_diff_logic.cpp b/src/smt/theory_diff_logic.cpp
index cb1812f9f..fd5bbd5da 100644
--- a/src/smt/theory_diff_logic.cpp
+++ b/src/smt/theory_diff_logic.cpp
@@ -28,7 +28,11 @@ template class theory_diff_logic<idl_ext>;
 template class theory_diff_logic<sidl_ext>;
 template class theory_diff_logic<rdl_ext>;
 template class theory_diff_logic<srdl_ext>;
-template class simplex::simplex<simplex::mpq_ext>;
 
 
+};
+
+namespace simplex {
+template class simplex<mpq_ext>;
+
 };