diff --git a/drivers/gpu/drm/vc4/vc4_perfmon.c b/drivers/gpu/drm/vc4/vc4_perfmon.c
index 437e7a27f21d..495150415020 100644
--- a/drivers/gpu/drm/vc4/vc4_perfmon.c
+++ b/drivers/gpu/drm/vc4/vc4_perfmon.c
@@ -117,7 +117,7 @@ int vc4_perfmon_create_ioctl(struct drm_device *dev, void *data,
 			return -EINVAL;
 	}
 
-	perfmon = kzalloc(sizeof(*perfmon) + (req->ncounters * sizeof(u64)),
+	perfmon = kzalloc(struct_size(perfmon, counters, req->ncounters),
 			  GFP_KERNEL);
 	if (!perfmon)
 		return -ENOMEM;