diff --git a/intel/intel_bufmgr_gem.c b/intel/intel_bufmgr_gem.c
index c5bb588..310076e 100644
--- a/intel/intel_bufmgr_gem.c
+++ b/intel/intel_bufmgr_gem.c
@@ -1552,6 +1552,22 @@ drm_intel_gem_bo_exec(drm_intel_bo *bo, int used,
 	return ret;
 }
 
+static void validate_exec_list(struct drm_i915_gem_exec_object2 *objects,
+			       int count)
+{
+	int i, j;
+
+	for (i = 0; i < count; i++) {
+		for (j = i + 1; j < count; j++) {
+			if (objects[i].handle == objects[j].handle) {
+				fprintf(stderr, "object [%d] occurs more than once in list at %d and %d\n",
+					objects[i].handle, i, j);
+				assert(0);
+			}
+		}
+	}
+}
+
 static int
 drm_intel_gem_bo_mrb_exec2(drm_intel_bo *bo, int used,
 			drm_clip_rect_t *cliprects, int num_cliprects, int DR4,
@@ -1585,6 +1601,8 @@ drm_intel_gem_bo_mrb_exec2(drm_intel_bo *bo, int used,
 	 * pointing to it.
 	 */
 	drm_intel_add_validate_buffer2(bo, 0);
+	validate_exec_list(bufmgr_gem->exec2_objects,
+			   bufmgr_gem->exec_count);
 
 	execbuf.buffers_ptr = (uintptr_t)bufmgr_gem->exec2_objects;
 	execbuf.buffer_count = bufmgr_gem->exec_count;