diff --git a/lib/base/tlsutility.cpp b/lib/base/tlsutility.cpp
index 91723b65b..ce2e459a0 100644
--- a/lib/base/tlsutility.cpp
+++ b/lib/base/tlsutility.cpp
@@ -899,19 +899,4 @@ Array::Ptr GetSubjectAltNames(const std::shared_ptr<X509>& cert)
 	return sans;
 }
 
-std::string to_string(const errinfo_openssl_error& e)
-{
-	std::ostringstream tmp;
-	int code = e.value();
-	char errbuf[120];
-
-	const char *message = ERR_error_string(code, errbuf);
-
-	if (!message)
-		message = "Unknown error.";
-
-	tmp << code << ", \"" << message << "\"";
-	return "[errinfo_openssl_error]" + tmp.str() + "\n";
-}
-
 }
diff --git a/lib/base/tlsutility.hpp b/lib/base/tlsutility.hpp
index a923311d0..665f4e794 100644
--- a/lib/base/tlsutility.hpp
+++ b/lib/base/tlsutility.hpp
@@ -62,8 +62,6 @@ class openssl_error : virtual public std::exception, virtual public boost::excep
 struct errinfo_openssl_error_;
 typedef boost::error_info<struct errinfo_openssl_error_, unsigned long> errinfo_openssl_error;
 
-std::string to_string(const errinfo_openssl_error& e);
-
 }
 
 #endif /* TLSUTILITY_H */