diff --git a/src/arch/riscv/isa/vector/base/vector_mem.temp.isa b/src/arch/riscv/isa/vector/base/vector_mem.temp.isa
index a8e5b71f99..e97eef0940 100644
--- a/src/arch/riscv/isa/vector/base/vector_mem.temp.isa
+++ b/src/arch/riscv/isa/vector/base/vector_mem.temp.isa
@@ -423,6 +423,8 @@ def template VlWholeConstructor {{
 %(class_name)s::%(class_name)s(ExtMachInst _machInst)
     : %(base_class)s("%(mnemonic)s", _machInst, %(op_class)s)
 {
+    %(set_reg_idx_arr)s;
+
     size_t NFIELDS = machInst.nf + 1;
     eew = 8;
     StaticInstPtr microop;