diff --git a/kernel/tclapi.cc b/kernel/tclapi.cc
index 13d00bca6..a905da606 100644
--- a/kernel/tclapi.cc
+++ b/kernel/tclapi.cc
@@ -22,7 +22,7 @@
 #include "libs/json11/json11.hpp"
 
 #ifdef YOSYS_ENABLE_TCL
-#define CONST const
+#include "tcl.h"
 #include "tclTomMath.h"
 #include "tclTomMathDecls.h"
 #endif