diff -Naur a/src/microhttpd/connection.c b/src/microhttpd/connection.c
--- a/src/microhttpd/connection.c	2016-04-08 21:02:26.000000000 +0200
+++ b/src/microhttpd/connection.c	2016-08-29 22:41:53.790560238 +0200
@@ -708,6 +708,8 @@
  * "keep-alive", we proceed to use the default for the respective HTTP
  * version (which is conservative for HTTP 1.0, but might be a bit
  * optimistic for HTTP 1.1).
+ * In the case of Upgrade, the header  Connection should not be set
+ * to keep-alive.
  *
  * @param connection the connection to check for keepalive
  * @return #MHD_YES if (based on the request), a keepalive is
@@ -750,6 +752,59 @@
 
 
 /**
+ * Should we try to keep the given connection alive?  We can use the
+ * TCP stream for a second request if the connection is HTTP 1.1 and
+ * the "Connection" header either does not exist or is not set to
+ * "close", or if the connection is HTTP 1.0 and the "Connection"
+ * header is explicitly set to "keep-alive".  If no HTTP version is
+ * specified (or if it is not 1.0 or 1.1), we definitively close the
+ * connection.  If the "Connection" header is not exactly "close" or
+ * "keep-alive", we proceed to use the default for the respective HTTP
+ * version (which is conservative for HTTP 1.0, but might be a bit
+ * optimistic for HTTP 1.1).
+ * In the case of Upgrade, the connection should be kept alive even if
+ * the header Connection is not keep-alive.
+ *
+ * @param connection the connection to check for keepalive
+ * @return #MHD_YES if (based on the request), a keepalive is
+ *        legal
+ */
+static int
+should_keepalive (struct MHD_Connection *connection)
+{
+  const char *end;
+
+  if (NULL == connection->version)
+    return MHD_NO;
+  if ( (NULL != connection->response) &&
+       (0 != (connection->response->flags & MHD_RF_HTTP_VERSION_1_0_ONLY) ) )
+    return MHD_NO;
+  end = MHD_lookup_connection_value (connection,
+                                     MHD_HEADER_KIND,
+                                     MHD_HTTP_HEADER_CONNECTION);
+  if (MHD_str_equal_caseless_(connection->version,
+                       MHD_HTTP_VERSION_1_1))
+  {
+    if (NULL == end)
+      return MHD_YES;
+    if ( (MHD_str_equal_caseless_ (end, "close")) )
+      return MHD_NO;
+   return MHD_YES;
+  }
+  if (MHD_str_equal_caseless_(connection->version,
+                       MHD_HTTP_VERSION_1_0))
+  {
+    if (NULL == end)
+      return MHD_NO;
+    if (MHD_str_equal_caseless_(end, "Keep-Alive"))
+      return MHD_YES;
+    return MHD_NO;
+  }
+  return MHD_NO;
+}
+
+
+/**
  * Produce HTTP "Date:" header.
  *
  * @param date where to write the header, with
@@ -2795,7 +2850,7 @@
             }
           if (((MHD_YES == connection->read_closed) &&
                (0 == connection->read_buffer_offset)) ||
-              (MHD_NO == keepalive_possible (connection)))
+              (MHD_NO == should_keepalive (connection)))
             {
               /* have to close for some reason */
               MHD_connection_close_ (connection,