Index: openacs-4/packages/acs-tcl/tcl/document-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/document-procs.tcl,v
diff -u -r1.7 -r1.8
--- openacs-4/packages/acs-tcl/tcl/document-procs.tcl	7 Aug 2017 23:47:59 -0000	1.7
+++ openacs-4/packages/acs-tcl/tcl/document-procs.tcl	1 Oct 2017 12:16:05 -0000	1.8
@@ -182,7 +182,7 @@
 	}
     }
 
-    switch $mime_type {
+    switch -- $mime_type {
 	text/html;content-pane - text/x-html-content-pane {
 	    # It's a content pane. Find the appropriate template.
 	    set template_path [doc_find_template [ad_conn file]]