diff --git a/src/gx/d3d/CGxDeviceD3d.cpp b/src/gx/d3d/CGxDeviceD3d.cpp
index b9ac1e9..eba30c1 100644
--- a/src/gx/d3d/CGxDeviceD3d.cpp
+++ b/src/gx/d3d/CGxDeviceD3d.cpp
@@ -368,6 +368,7 @@ char* CGxDeviceD3d::IBufLock(CGxBuf* buf) {
         } else {
             lockFlags = D3DLOCK_DISCARD;
             pool->Discard();
+            buf->m_index = 0;
             pool->unk1C = buf->m_size;
         }
     } else if (pool->m_usage == GxPoolUsage_Dynamic) {