Index: Source/cmFileCommand.cxx
--- Source/cmFileCommand.cxx.orig
+++ Source/cmFileCommand.cxx
@@ -1763,6 +1763,13 @@ bool HandleDownloadCommand(std::vector<std::string> co
   ++i;
   std::string file;
 
+  std::string openbsd_build;
+  if ((cmSystemTools::GetEnv("MODCMAKE_PORT_BUILD", openbsd_build) &&
+     openbsd_build == std::string("yes")) && !cmHasPrefix(url, "file:///")) {
+    status.SetError("DOWNLOAD not supported in OpenBSD ports builds.");
+    return false;
+  }
+
   long timeout = 0;
   long inactivity_timeout = 0;
   std::string logVar;
@@ -2173,6 +2180,12 @@ bool HandleUploadCommand(std::vector<std::string> cons
                          cmExecutionStatus& status)
 {
 #if !defined(CMAKE_BOOTSTRAP)
+  std::string openbsd_build;
+  if ((cmSystemTools::GetEnv("MODCMAKE_PORT_BUILD", openbsd_build) &&
+     openbsd_build == std::string("yes"))) {
+    status.SetError("UPLOAD not supported in OpenBSD ports builds.");
+    return false;
+  }
   if (args.size() < 3) {
     status.SetError("UPLOAD must be called with at least three arguments.");
     return false;