diff --git a/drmhwcgralloc.h b/drmhwcgralloc.h
index 759746a..daa44dc 100644
--- a/drmhwcgralloc.h
+++ b/drmhwcgralloc.h
@@ -19,14 +19,15 @@
 
 #include <stdint.h>
 
+#define HWC_DRM_BO_MAX_PLANES 4
 typedef struct hwc_drm_bo {
   uint32_t width;
   uint32_t height;
   uint32_t format; /* DRM_FORMAT_* from drm_fourcc.h */
   uint32_t usage;
-  uint32_t pitches[4];
-  uint32_t offsets[4];
-  uint32_t gem_handles[4];
+  uint32_t pitches[HWC_DRM_BO_MAX_PLANES];
+  uint32_t offsets[HWC_DRM_BO_MAX_PLANES];
+  uint32_t gem_handles[HWC_DRM_BO_MAX_PLANES];
   uint32_t fb_id;
   int acquire_fence_fd;
   void *priv;