diff --git a/Source/cmFileCommand.cxx b/Source/cmFileCommand.cxx
index 4797c06011..08baca060e 100644
--- a/Source/cmFileCommand.cxx
+++ b/Source/cmFileCommand.cxx
@@ -2131,7 +2131,10 @@ bool HandleDownloadCommand(std::vector<std::string> const& args,
   res = ::curl_easy_setopt(curl, CURLOPT_FAILONERROR, 1);
   check_curl_result(res, "DOWNLOAD cannot set http failure option: ");
 
-  res = ::curl_easy_setopt(curl, CURLOPT_USERAGENT, "curl/" LIBCURL_VERSION);
+  curl_version_info_data* cv = curl_version_info(CURLVERSION_FIRST);
+  res = ::curl_easy_setopt(
+    curl, CURLOPT_USERAGENT,
+    cmStrCat("curl/", cv ? cv->version : LIBCURL_VERSION).c_str());
   check_curl_result(res, "DOWNLOAD cannot set user agent option: ");
 
   res = ::curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, cmWriteToFileCallback);