diff --git a/src/s3access.cpp b/src/s3access.cpp
index a1ffb9d..3df6dc3 100644
--- a/src/s3access.cpp
+++ b/src/s3access.cpp
@@ -4,8 +4,11 @@ extern "C" {
 
 #include <QFile>
 
+// Needed for performOp
 #include "s3access.h"
 
+#include <openssl/hmac.h>
+
 S3Result::S3Result(QNetworkReply *reply, QObject *parent) : QObject(parent)
   , m_reply(reply)
 {
@@ -130,7 +133,7 @@ S3ListResult *S3Access::list(QString const &prefix)
 QNetworkReply *S3Access::performOp(Method method, QString const &url, QIODevice *in, const char *content_md5, const char *content_type, QString signDataKey)
 {
     QNetworkRequest request;
-    char *digest;
+    unsigned char digest[EVP_MAX_MD_SIZE];
     QString methodStr;
     QString date = QDateTime::currentDateTimeUtc().toString(Qt::RFC2822Date);
     QNetworkReply *reply;
@@ -157,10 +160,10 @@ QNetworkReply *S3Access::performOp(Method method, QString const &url, QIODevice
         signData+=signDataKey;
 
     request.setUrl(QUrl(QString(url)));
-    digest = s3_hmac_sign(m_secret.toLatin1().data(), signData.toLatin1().data(), signData.toLatin1().size());
+    HMAC(EVP_sha1(), m_secret.toLatin1().data(), m_secret.toLatin1().size(), (unsigned char*)signData.toLatin1().data(), signData.toLatin1().size(), digest, (unsigned int*)EVP_MAX_MD_SIZE);
 
     request.setRawHeader("Date", date.toLocal8Bit());
-    request.setRawHeader("Authorization", QString(QStringLiteral("AWS %1:%2")).arg(m_id).arg(digest).toLocal8Bit());
+    request.setRawHeader("Authorization", QString(QStringLiteral("AWS %1:%2")).arg(m_id).arg((char*)digest).toLocal8Bit());
     request.setAttribute(QNetworkRequest::FollowRedirectsAttribute, true);
 
     qDebug() << "Request to: " << url;
@@ -188,7 +191,6 @@ QNetworkReply *S3Access::performOp(Method method, QString const &url, QIODevice
         break;
     }
 
-    free(digest);
 
     return reply;
 }