diff --git a/frontends/verilog/verilog_lexer.l b/frontends/verilog/verilog_lexer.l
index e344ffd4f..4acfb414d 100644
--- a/frontends/verilog/verilog_lexer.l
+++ b/frontends/verilog/verilog_lexer.l
@@ -239,7 +239,7 @@ YOSYS_NAMESPACE_END
 	return TOK_CONSTVAL;
 }
 
-[0-9]*[ \t]*\'[sS]?[bodhBODH][ \t\r\n]*[0-9a-fA-FzxZX?_]+ {
+[0-9]*[ \t]*\'[sS]?[bodhBODH]?[ \t\r\n]*[0-9a-fA-FzxZX?_]+ {
 	frontend_verilog_yylval.string = new std::string(yytext);
 	return TOK_CONSTVAL;
 }