1 files changed, 2 insertions, 2 deletions
diff --git a/src/pubkey/pubkey.cpp b/src/pubkey/pubkey.cpp
index 6e63f9fc9..d0b74071c 100644
--- a/src/pubkey/pubkey.cpp
+++ b/src/pubkey/pubkey.cpp
@@ -238,7 +238,7 @@ SecureVector<byte> PK_Signer::signature(RandomNumberGenerator& rng)
       }
    else
       throw Encoding_Error("PK_Signer: Unknown signature format " +
-                           to_string(sig_format));
+                           std::to_string(sig_format));
    }
 
 /*
@@ -324,7 +324,7 @@ bool PK_Verifier::check_signature(const byte sig[], size_t length)
          }
       else
          throw Decoding_Error("PK_Verifier: Unknown signature format " +
-                              to_string(sig_format));
+                              std::to_string(sig_format));
       }
    catch(Invalid_Argument) { return false; }
    }