diff --git a/frontends/ilang/lexer.l b/frontends/ilang/lexer.l
index 00091927..6557f98a 100644
--- a/frontends/ilang/lexer.l
+++ b/frontends/ilang/lexer.l
@@ -23,9 +23,16 @@
  */
 
 %{
+
+#ifdef __clang__
+// bison generates code using the 'register' storage class specifier
+#pragma clang diagnostic ignored "-Wdeprecated-register"
+#endif
+
 #include "kernel/rtlil.h"
 #include "parser.tab.h"
 void update_autoidx(const char *p);
+
 %}
 
 %option yylineno
diff --git a/frontends/verilog/lexer.l b/frontends/verilog/lexer.l
index e3e5e4ab..226a2670 100644
--- a/frontends/verilog/lexer.l
+++ b/frontends/verilog/lexer.l
@@ -34,6 +34,11 @@
 
 %{
 
+#ifdef __clang__
+// bison generates code using the 'register' storage class specifier
+#pragma clang diagnostic ignored "-Wdeprecated-register"
+#endif
+
 #include "kernel/log.h"
 #include "verilog_frontend.h"
 #include "frontends/ast/ast.h"