Index: openacs-4/packages/acs-content-repository/tcl/revision-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-content-repository/tcl/revision-procs.tcl,v
diff -u -r1.37.2.6 -r1.37.2.7
--- openacs-4/packages/acs-content-repository/tcl/revision-procs.tcl	2 Mar 2021 14:17:49 -0000	1.37.2.6
+++ openacs-4/packages/acs-content-repository/tcl/revision-procs.tcl	1 Apr 2022 13:57:48 -0000	1.37.2.7
@@ -140,9 +140,10 @@
         # but work around it for now.
         set size [file size $filename]
         if {$size == 0} {
-            ns_set put [ns_conn outputheaders] "Content-Length" 0
+            ns_set iupdate [ns_conn outputheaders] "Content-Length" 0
             ns_return 200 text/plain {}
         } else {
+            ::security::csp::add_static_resource_header -mime_type $mime_type
             if {[namespace which ad_returnfile_background] eq "" || [security::secure_conn_p]} {
                 ns_returnfile 200 $mime_type $filename
             } else {