diff --git a/tools/perf/util/trace-event-parse.c b/tools/perf/util/trace-event-parse.c
index eae5605..7021dc1 100644
--- a/tools/perf/util/trace-event-parse.c
+++ b/tools/perf/util/trace-event-parse.c
@@ -941,7 +941,8 @@
 			if (read_expect_type(EVENT_ITEM, &token))
 				goto fail;
 
-			/* add signed type */
+			if (strtoul(token, NULL, 0))
+				field->flags |= FIELD_IS_SIGNED;
 
 			free_token(token);
 			if (read_expected(EVENT_OP, ";") < 0)