1 files changed, 1 insertions, 1 deletions
diff --git a/verifier.cpp b/verifier.cpp
index 8be6da09f..2ef9c4c37 100644
--- a/verifier.cpp
+++ b/verifier.cpp
@@ -376,7 +376,7 @@ std::unique_ptr<RSA, RSADeleter> parse_rsa_key(FILE* file, uint32_t exponent) {
 }
 
 struct BNDeleter {
-  void operator()(BIGNUM* bn) {
+  void operator()(BIGNUM* bn) const {
     BN_free(bn);
   }
 };