diff --git a/ChangeLog b/ChangeLog
index c6ca1edcd..3c2e568c7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2021-05-15 Richard Frith-Macdonald <rfm@gnu.org>
+
+	* Source/GSFileHandle.m:
+	* Source/win32/GSFileHandle.m:
+	When we receive an event telling us the handle is writable, repeatedly
+	write until either all the data we have is written or until the write
+	attempt doesn't write anything.  On mswindows this copes with the case
+	of the gnutls write only writing 16KB chunks at a time.
+
 2021-05-05 Richard Frith-Macdonald <rfm@gnu.org>
 
 	* configure.ac: Check for declaration of CURLOPT_MAXAGE_CONN
diff --git a/Source/GSFileHandle.m b/Source/GSFileHandle.m
index c8cc9651c..ede5318fc 100644
--- a/Source/GSFileHandle.m
+++ b/Source/GSFileHandle.m
@@ -2264,7 +2264,7 @@ NSString * const GSSOCKSRecvAddr = @"GSSOCKSRecvAddr";
       item = [info objectForKey: NSFileHandleNotificationDataItem];
       length = [item length];
       ptr = [item bytes];
-      if (writePos < length)
+      while (writePos < length)
         {
           int	written;
 
diff --git a/Source/win32/GSFileHandle.m b/Source/win32/GSFileHandle.m
index f01cd1800..e7332b0bc 100644
--- a/Source/win32/GSFileHandle.m
+++ b/Source/win32/GSFileHandle.m
@@ -2220,7 +2220,7 @@ NSString * const GSSOCKSRecvAddr = @"GSSOCKSRecvAddr";
       item = [info objectForKey: NSFileHandleNotificationDataItem];
       length = [item length];
       ptr = [item bytes];
-      if (writePos < length)
+      while (writePos < length)
         {
           int	written;