diff --git a/src/muz/rel/dl_interval_relation.cpp b/src/muz/rel/dl_interval_relation.cpp
index ccb7b728b..e14d242bb 100644
--- a/src/muz/rel/dl_interval_relation.cpp
+++ b/src/muz/rel/dl_interval_relation.cpp
@@ -18,7 +18,6 @@ Revision History:
 --*/
 
 #include "util/debug.h"
-#include "util/optional.h"
 #include "ast/ast_pp.h"
 #include "muz/rel/dl_interval_relation.h"
 #include "muz/rel/dl_relation_manager.h"
diff --git a/src/util/optional.h b/src/util/optional.h
index eeff35260..5b3753ac6 100644
--- a/src/util/optional.h
+++ b/src/util/optional.h
@@ -21,7 +21,7 @@ Revision History:
 #ifndef OPTIONAL_H_
 #define OPTIONAL_H_
 
-template<typename T>
+template<class T>
 class optional {
     T* m_obj;
     char m_initialized;