Index: OrthancFramework/Sources/DicomNetworking/Internals/DicomTls.cpp
--- OrthancFramework/Sources/DicomNetworking/Internals/DicomTls.cpp.orig
+++ OrthancFramework/Sources/DicomNetworking/Internals/DicomTls.cpp
@@ -230,6 +230,9 @@ namespace Orthanc
         }
 
         DcmTLSTransportLayer::native_handle_type sslNativeHandle = tls->getNativeHandle();
+#ifndef SSL_OP_NO_SSL_MASK
+#define SSL_OP_NO_SSL_MASK (SSL_OP_NO_TLSv1_2|SSL_OP_NO_TLSv1_3)
+#endif
         SSL_CTX_clear_options(sslNativeHandle, SSL_OP_NO_SSL_MASK);
         if (minimalTlsVersion > 1) 
         {
