diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c
index c8ccc548a585..c3382d58cf40 100644
--- a/tools/perf/util/expr.c
+++ b/tools/perf/util/expr.c
@@ -3,7 +3,6 @@
 #include <assert.h>
 #include "expr.h"
 #include "expr-bison.h"
-#define YY_EXTRA_TYPE int
 #include "expr-flex.h"
 
 #ifdef PARSER_DEBUG
@@ -30,11 +29,14 @@ static int
 __expr__parse(double *val, struct expr_parse_ctx *ctx, const char *expr,
 	      int start)
 {
+	struct expr_scanner_ctx scanner_ctx = {
+		.start_token = start,
+	};
 	YY_BUFFER_STATE buffer;
 	void *scanner;
 	int ret;
 
-	ret = expr_lex_init_extra(start, &scanner);
+	ret = expr_lex_init_extra(&scanner_ctx, &scanner);
 	if (ret)
 		return ret;
 
diff --git a/tools/perf/util/expr.h b/tools/perf/util/expr.h
index b9e53f2b5844..0938ad166ece 100644
--- a/tools/perf/util/expr.h
+++ b/tools/perf/util/expr.h
@@ -15,6 +15,10 @@ struct expr_parse_ctx {
 	struct expr_parse_id ids[MAX_PARSE_ID];
 };
 
+struct expr_scanner_ctx {
+	int start_token;
+};
+
 void expr__ctx_init(struct expr_parse_ctx *ctx);
 void expr__add_id(struct expr_parse_ctx *ctx, const char *id, double val);
 int expr__parse(double *final_val, struct expr_parse_ctx *ctx, const char *expr);
diff --git a/tools/perf/util/expr.l b/tools/perf/util/expr.l
index eaad29243c23..2582c2464938 100644
--- a/tools/perf/util/expr.l
+++ b/tools/perf/util/expr.l
@@ -76,13 +76,13 @@ sym		[0-9a-zA-Z_\.:@]+
 symbol		{spec}*{sym}*{spec}*{sym}*
 
 %%
+	struct expr_scanner_ctx *sctx = expr_get_extra(yyscanner);
+
 	{
-		int start_token;
+		int start_token = sctx->start_token;
 
-		start_token = expr_get_extra(yyscanner);
-
-		if (start_token) {
-			expr_set_extra(NULL, yyscanner);
+		if (sctx->start_token) {
+			sctx->start_token = 0;
 			return start_token;
 		}
 	}