diff --git a/unix/xserver/hw/vnc/Xvnc.man b/unix/xserver/hw/vnc/Xvnc.man
index adfd560..0689367 100644
--- a/unix/xserver/hw/vnc/Xvnc.man
+++ b/unix/xserver/hw/vnc/Xvnc.man
@@ -110,7 +110,7 @@ Run a mini-HTTP server which serves files from the given directory.  Normally
 the directory will contain the kasmweb client. It will use the websocket port.
 .
 .TP
-.B \-H \fIheader=val\fP
+.B \-http-header \fIheader=val\fP
 Append this header to all HTTP responses (file and API). May be given multiple
 times.
 .
diff --git a/unix/xserver/hw/vnc/xvnc.c b/unix/xserver/hw/vnc/xvnc.c
index e11b6a3..5f293f9 100644
--- a/unix/xserver/hw/vnc/xvnc.c
+++ b/unix/xserver/hw/vnc/xvnc.c
@@ -362,7 +362,7 @@ void ddxUseMsg(void)
     ErrorF("-depth D               set screen 0's depth\n");
     ErrorF("-pixelformat fmt       set pixel format (rgbNNN or bgrNNN)\n");
     ErrorF("-inetd                 has been launched from inetd\n");
-    ErrorF("-H header=val          append this header to all HTTP responses\n");
+    ErrorF("-http-header name=val  append this header to all HTTP responses\n");
     ErrorF("-noclipboard           disable clipboard settings modification via vncconfig utility\n");
     ErrorF("-verbose [n]           verbose startup messages\n");
     ErrorF("-quiet                 minimal startup messages\n");
@@ -574,7 +574,7 @@ ddxProcessArgument(int argc, char *argv[], int i)
 	return 2;
     }
 
-    if (strcmp(argv[i], "-H") == 0)
+    if (strcmp(argv[i], "-http-header") == 0)
     {
         fail_unless_args(argc, i, 1);
         ++i;