diff --git a/src/ir_opt/verification_pass.cpp b/src/ir_opt/verification_pass.cpp
index d81df787..585c7a66 100644
--- a/src/ir_opt/verification_pass.cpp
+++ b/src/ir_opt/verification_pass.cpp
@@ -20,8 +20,8 @@ void VerificationPass(const IR::Block& block) {
     for (const auto& inst : block) {
         const size_t num_args = inst.NumArgs();
         for (size_t i = 0; i < num_args; i++) {
-            IR::Type t1 = inst.GetArg(i).GetType();
-            IR::Type t2 = IR::GetArgTypeOf(inst.GetOpcode(), i);
+            const IR::Type t1 = inst.GetArg(i).GetType();
+            const IR::Type t2 = IR::GetArgTypeOf(inst.GetOpcode(), i);
             if (!IR::AreTypesCompatible(t1, t2)) {
                 puts(IR::DumpBlock(block).c_str());
                 ASSERT(false);