diff --git a/backends/functional/smtlib.cc b/backends/functional/smtlib.cc
index f6af797919b..cd11111b9d8 100644
--- a/backends/functional/smtlib.cc
+++ b/backends/functional/smtlib.cc
@@ -17,6 +17,7 @@
  *
  */
 
+#include <cassert>
 #include "kernel/yosys.h"
 #include "kernel/drivertools.h"
 #include "kernel/topo_scc.h"