diff --git a/src/main/scala/xiangshan/backend/fu/CSR.scala b/src/main/scala/xiangshan/backend/fu/CSR.scala
index 2b894e9af65a6ffba8d5f4ef3047df3556fbab14..18132c88ed682227896b83fc88d5987bd5b579aa 100644
--- a/src/main/scala/xiangshan/backend/fu/CSR.scala
+++ b/src/main/scala/xiangshan/backend/fu/CSR.scala
@@ -491,7 +491,7 @@ class CSR extends FunctionUnit with HasCSRConst
                 (if (HasFPU) fcsrMapping else Nil)
 
   val addr = src2(11, 0)
-  val csri = src2(16, 12)
+  val csri = ZeroExt(src2(16, 12), XLEN)
   val rdata = Wire(UInt(XLEN.W))
   val wdata = LookupTree(func, List(
     CSROpType.wrt  -> src1,