diff --git a/checkin_notes b/checkin_notes
index 869c368884..f7e08f1329 100644
--- a/checkin_notes
+++ b/checkin_notes
@@ -6303,3 +6303,23 @@ David  16 July 2009
     lib/
         gui_rpc_client_ops.cpp
         gui_rpc_client.h
+
+David  16 July 2009
+    - client: changed file upload logic
+        Old: each upload attempt consists of two HTTP requests:
+            the 1st to get the current file size on server,
+            the 2nd to upload the remainder of the file.
+        Problem:
+            a) if the upload server is overloaded and requests
+                are succeeding with probability X,
+                then the chance of both requests succeeding is X^2.
+                So e.g. a per-request success rate of 0.1
+                becomes an overall success rate of 0.01.
+            b) the "get file size" request can be avoided in some cases.
+        New:
+            If we've already queried the file size
+            and haven't uploaded any additional bytes,
+            don't query the file size again.
+
+    client/
+        pers_file_xfer.cpp
diff --git a/client/pers_file_xfer.cpp b/client/pers_file_xfer.cpp
index d9c4b60517..0891433fe7 100644
--- a/client/pers_file_xfer.cpp
+++ b/client/pers_file_xfer.cpp
@@ -191,7 +191,6 @@ bool PERS_FILE_XFER::poll() {
             return false;
         }
         last_time = gstate.now;
-        fip->upload_offset = -1;
         retval = create_xfer();
         return (retval == 0);
     }
@@ -269,6 +268,14 @@ bool PERS_FILE_XFER::poll() {
             transient_failure(fxp->file_xfer_retval);
         }
 
+        // If we transferred any bytes, set upload_offset back to -1
+        // so that we'll query file size on next retry.
+        // Otherwise leave it as is, avoiding unnecessary size query.
+        //
+        if (fxp->bytes_xferred) {
+            fip->upload_offset = -1;
+        }
+
         // fxp could have already been freed and zeroed above
         // so check before trying to remove
         //