diff --git a/drivers/gpu/drm/nouveau/nv50_instmem.c b/drivers/gpu/drm/nouveau/nv50_instmem.c
index a7c12c9..0bba54f 100644
--- a/drivers/gpu/drm/nouveau/nv50_instmem.c
+++ b/drivers/gpu/drm/nouveau/nv50_instmem.c
@@ -83,7 +83,7 @@
 		return ret;
 	}
 
-	ret = drm_mm_init(&chan->ramin_heap, 0x6000, chan->ramin->size);
+	ret = drm_mm_init(&chan->ramin_heap, 0x6000, chan->ramin->size - 0x6000);
 	if (ret) {
 		nv50_channel_del(&chan);
 		return ret;