diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index 634b7f7..9e8995e 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -36,7 +36,10 @@
 	if (self->comm)
 		free(self->comm);
 	self->comm = strdup(comm);
-	return self->comm ? 0 : -ENOMEM;
+	if (self->comm == NULL)
+		return -ENOMEM;
+	self->comm_set = true;
+	return 0;
 }
 
 int thread__comm_len(struct thread *self)
@@ -255,11 +258,14 @@
 {
 	int i;
 
-	if (self->comm)
-		free(self->comm);
-	self->comm = strdup(parent->comm);
-	if (!self->comm)
-		return -ENOMEM;
+	if (parent->comm_set) {
+		if (self->comm)
+			free(self->comm);
+		self->comm = strdup(parent->comm);
+		if (!self->comm)
+			return -ENOMEM;
+		self->comm_set = true;
+	}
 
 	for (i = 0; i < MAP__NR_TYPES; ++i)
 		if (map_groups__clone(&self->mg, &parent->mg, i) < 0)
diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
index 56f317b..0a28f39 100644
--- a/tools/perf/util/thread.h
+++ b/tools/perf/util/thread.h
@@ -15,6 +15,7 @@
 	struct map_groups	mg;
 	pid_t			pid;
 	char			shortname[3];
+	bool			comm_set;
 	char			*comm;
 	int			comm_len;
 };