diff --git a/simgear/io/HTTPFileRequest.cxx b/simgear/io/HTTPFileRequest.cxx
index 22b25b16..b594774e 100644
--- a/simgear/io/HTTPFileRequest.cxx
+++ b/simgear/io/HTTPFileRequest.cxx
@@ -30,9 +30,7 @@ namespace HTTP
   FileRequest::FileRequest(const std::string& url, const std::string& path, bool append):
     Request(url, "GET"),
     _filename(path),
-    _append(append),
-    _callback(nullptr),
-    _callback_ref(nullptr)
+    _append(append)
   {
     if (append && _filename.isFile()) {
       size_t size = _filename.sizeInBytes();
@@ -45,10 +43,13 @@ namespace HTTP
     }
   }
 
-  void FileRequest::setCallback(Callback callback, void* ref)
+  void FileRequest::setCallback(std::function<void(const void* data, size_t numbytes)> callback)
   {
     _callback = callback;
-    _callback_ref = ref;
+    if (readyState() == DONE) {
+        SG_LOG(SG_GENERAL, SG_DEBUG, "making callback because readyState() == DONE");
+        _callback(nullptr, 0);
+    }
   }
 
   //----------------------------------------------------------------------------
@@ -67,12 +68,12 @@ namespace HTTP
     }
     else if (_append && (responseCode() == 206 || responseCode() == 416)) {
       /* See comments for simgear::HTTP::Client::setRange(). */
-      SG_LOG(SG_IO, SG_ALERT, "_append is true so treating response code as success: "
+      SG_LOG(SG_IO, SG_DEBUG, "_append is true so treating response code as success: "
           << responseCode());
       ok = true;
     }
     if (!ok) {
-      SG_LOG(SG_GENERAL, SG_ALERT, "failure. calling setFailure()."
+      SG_LOG(SG_GENERAL, SG_DEBUG, "failure. calling setFailure()."
           << " responseCode()=" << responseCode()
           << " responseReason()=" << responseReason()
           );
@@ -116,7 +117,7 @@ namespace HTTP
 
     _file.write(s, n);
     if (_callback) {
-      _callback(_callback_ref, s, n);
+        _callback(s, n);
     }
   }
 
@@ -125,7 +126,7 @@ namespace HTTP
   {
     _file.close();
     if (_callback) {
-      _callback(_callback_ref, nullptr, 0);
+        _callback(nullptr, 0);
     }
   }
 
diff --git a/simgear/io/HTTPFileRequest.hxx b/simgear/io/HTTPFileRequest.hxx
index 3c9c463e..422547e9 100644
--- a/simgear/io/HTTPFileRequest.hxx
+++ b/simgear/io/HTTPFileRequest.hxx
@@ -53,23 +53,18 @@ namespace HTTP
       FileRequest(const std::string& url, const std::string& path, bool append=false);
       
       /*
-       * Function pointer type for use with setCallback().
+       * Set callback for each chunk of data we receive. Called with (nullptr,
+       * 0) when download has completed (successfully or unsuccesfully) - this
+       * will be done from inside setCallback() if the download has already
+       * finished.
        */
-      typedef void (*Callback)(void* ref, const void* data, size_t numbytes);
+      void setCallback(std::function<void(const void* data, size_t numbytes)> callbackf);
       
-      /*
-       * Set callback for each chunk of data we receive. Called with
-       * (ref, nullptr, 0) when download has completed (successfully or
-       * unsuccesfully).
-       */
-      void setCallback(Callback callback, void* ref);
-
     protected:
       SGPath _filename;
       sg_ofstream _file;
       bool _append;
-      Callback _callback;
-      void* _callback_ref;
+      std::function<void(const void* data, size_t numbytes)> _callback;
 
       virtual void responseHeadersComplete();
       virtual void gotBodyData(const char* s, int n);