diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index afbd5869f6bf..ee0d5064ddd4 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -1074,8 +1074,8 @@ static void arm_spe_print_info(__u64 *arr)
 }
 
 struct arm_spe_synth {
-	struct perf_tool dummy_tool;
 	struct perf_session *session;
+	struct perf_tool dummy_tool[0];
 };
 
 static int arm_spe_event_synth(struct perf_tool *tool,
@@ -1084,7 +1084,7 @@ static int arm_spe_event_synth(struct perf_tool *tool,
 			       struct machine *machine __maybe_unused)
 {
 	struct arm_spe_synth *arm_spe_synth =
-		      container_of(tool, struct arm_spe_synth, dummy_tool);
+		      container_of(tool, struct arm_spe_synth, dummy_tool[0]);
 
 	return perf_session__deliver_synth_event(arm_spe_synth->session,
 						 event, NULL);
@@ -1098,7 +1098,7 @@ static int arm_spe_synth_event(struct perf_session *session,
 	memset(&arm_spe_synth, 0, sizeof(struct arm_spe_synth));
 	arm_spe_synth.session = session;
 
-	return perf_event__synthesize_attr(&arm_spe_synth.dummy_tool, attr, 1,
+	return perf_event__synthesize_attr(arm_spe_synth.dummy_tool, attr, 1,
 					   &id, arm_spe_event_synth);
 }
 
diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 32818bd7cd17..9fd2967d4e3f 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1596,8 +1596,8 @@ static int cs_etm__synth_branch_sample(struct cs_etm_queue *etmq,
 }
 
 struct cs_etm_synth {
-	struct perf_tool dummy_tool;
 	struct perf_session *session;
+	struct perf_tool dummy_tool[0];
 };
 
 static int cs_etm__event_synth(struct perf_tool *tool,
@@ -1606,7 +1606,7 @@ static int cs_etm__event_synth(struct perf_tool *tool,
 			       struct machine *machine __maybe_unused)
 {
 	struct cs_etm_synth *cs_etm_synth =
-		      container_of(tool, struct cs_etm_synth, dummy_tool);
+		      container_of(tool, struct cs_etm_synth, dummy_tool[0]);
 
 	return perf_session__deliver_synth_event(cs_etm_synth->session,
 						 event, NULL);
@@ -1620,7 +1620,7 @@ static int cs_etm__synth_event(struct perf_session *session,
 	memset(&cs_etm_synth, 0, sizeof(struct cs_etm_synth));
 	cs_etm_synth.session = session;
 
-	return perf_event__synthesize_attr(&cs_etm_synth.dummy_tool, attr, 1,
+	return perf_event__synthesize_attr(cs_etm_synth.dummy_tool, attr, 1,
 					   &id, cs_etm__event_synth);
 }
 
diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c
index ec1b3bd9f530..fb8fec3a3c36 100644
--- a/tools/perf/util/intel-bts.c
+++ b/tools/perf/util/intel-bts.c
@@ -738,8 +738,8 @@ static bool intel_bts_evsel_is_auxtrace(struct perf_session *session,
 }
 
 struct intel_bts_synth {
-	struct perf_tool dummy_tool;
 	struct perf_session *session;
+	struct perf_tool dummy_tool[0];
 };
 
 static int intel_bts_event_synth(struct perf_tool *tool,
@@ -748,7 +748,7 @@ static int intel_bts_event_synth(struct perf_tool *tool,
 				 struct machine *machine __maybe_unused)
 {
 	struct intel_bts_synth *intel_bts_synth =
-			container_of(tool, struct intel_bts_synth, dummy_tool);
+			container_of(tool, struct intel_bts_synth, dummy_tool[0]);
 
 	return perf_session__deliver_synth_event(intel_bts_synth->session,
 						 event, NULL);
@@ -762,7 +762,7 @@ static int intel_bts_synth_event(struct perf_session *session,
 	memset(&intel_bts_synth, 0, sizeof(struct intel_bts_synth));
 	intel_bts_synth.session = session;
 
-	return perf_event__synthesize_attr(&intel_bts_synth.dummy_tool, attr, 1,
+	return perf_event__synthesize_attr(intel_bts_synth.dummy_tool, attr, 1,
 					   &id, intel_bts_event_synth);
 }
 
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index d6d7b7512505..b8b90773baa2 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -3660,8 +3660,8 @@ static int intel_pt_queue_data(struct perf_session *session,
 }
 
 struct intel_pt_synth {
-	struct perf_tool dummy_tool;
 	struct perf_session *session;
+	struct perf_tool dummy_tool[0];
 };
 
 static int intel_pt_event_synth(struct perf_tool *tool,
@@ -3670,7 +3670,7 @@ static int intel_pt_event_synth(struct perf_tool *tool,
 				struct machine *machine __maybe_unused)
 {
 	struct intel_pt_synth *intel_pt_synth =
-			container_of(tool, struct intel_pt_synth, dummy_tool);
+			container_of(tool, struct intel_pt_synth, dummy_tool[0]);
 
 	return perf_session__deliver_synth_event(intel_pt_synth->session, event,
 						 NULL);
@@ -3687,8 +3687,7 @@ static int intel_pt_synth_event(struct perf_session *session, const char *name,
 
 	memset(&intel_pt_synth, 0, sizeof(struct intel_pt_synth));
 	intel_pt_synth.session = session;
-
-	err = perf_event__synthesize_attr(&intel_pt_synth.dummy_tool, attr, 1,
+	err = perf_event__synthesize_attr(intel_pt_synth.dummy_tool, attr, 1,
 					  &id, intel_pt_event_synth);
 	if (err)
 		pr_err("%s: failed to synthesize '%s' event type\n",
diff --git a/tools/perf/util/s390-cpumsf.c b/tools/perf/util/s390-cpumsf.c
index 6fe478b0b61b..4ec583e511af 100644
--- a/tools/perf/util/s390-cpumsf.c
+++ b/tools/perf/util/s390-cpumsf.c
@@ -952,11 +952,6 @@ s390_cpumsf_process_event(struct perf_session *session,
 	return err;
 }
 
-struct s390_cpumsf_synth {
-	struct perf_tool cpumsf_tool;
-	struct perf_session *session;
-};
-
 static int
 s390_cpumsf_process_auxtrace_event(struct perf_session *session,
 				   union perf_event *event __maybe_unused,
