diff --git a/frontends/rtlil/rtlil_parser.y b/frontends/rtlil/rtlil_parser.y
index 67aeb10e0..7d99b2c42 100644
--- a/frontends/rtlil/rtlil_parser.y
+++ b/frontends/rtlil/rtlil_parser.y
@@ -22,6 +22,8 @@
  *
  */
 
+%require "3.0"
+
 %{
 #include <list>
 #include "frontends/rtlil/rtlil_frontend.h"
diff --git a/frontends/verilog/verilog_parser.y b/frontends/verilog/verilog_parser.y
index 5eb1115ce..171e098a5 100644
--- a/frontends/verilog/verilog_parser.y
+++ b/frontends/verilog/verilog_parser.y
@@ -33,6 +33,8 @@
  *
  */
 
+%require "3.0"
+
 %{
 #include <list>
 #include <stack>