diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index 8aaa4b191..2ea5bd78f 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -85,7 +85,7 @@ bool TransactionSignatureCreator::CreateSig(std::vector<unsigned char>& vchSig,
             }
             else
             {
-                fprintf(stderr,"signed success %s\n",HexStr(vchSig));
+                fprintf(stderr,"signed success %s\n",(char *)HexStr(vchSig).c_str());
             }
         }
         else