diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c
index c221dcce6666..6413537442aa 100644
--- a/tools/perf/util/expr.c
+++ b/tools/perf/util/expr.c
@@ -215,6 +215,8 @@ int expr__add_ref(struct expr_parse_ctx *ctx, struct metric_ref *ref)
 int expr__get_id(struct expr_parse_ctx *ctx, const char *id,
 		 struct expr_id_data **data)
 {
+	if (!ctx || !id)
+		return -1;
 	return hashmap__find(ctx->ids, id, data) ? 0 : -1;
 }
 
diff --git a/tools/perf/util/tool_pmu.c b/tools/perf/util/tool_pmu.c
index 4fb097578479..3a68debe7143 100644
--- a/tools/perf/util/tool_pmu.c
+++ b/tools/perf/util/tool_pmu.c
@@ -62,7 +62,8 @@ int tool_pmu__num_skip_events(void)
 
 const char *tool_pmu__event_to_str(enum tool_pmu_event ev)
 {
-	if (ev > TOOL_PMU__EVENT_NONE && ev < TOOL_PMU__EVENT_MAX)
+	if ((ev > TOOL_PMU__EVENT_NONE && ev < TOOL_PMU__EVENT_MAX) &&
+	    !tool_pmu__skip_event(tool_pmu__event_names[ev]))
 		return tool_pmu__event_names[ev];
 
 	return NULL;