Index: openacs-4/packages/acs-tcl/tcl/00-icanuse-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/00-icanuse-procs.tcl,v
diff -u -r1.1.2.21 -r1.1.2.22
--- openacs-4/packages/acs-tcl/tcl/00-icanuse-procs.tcl	14 Jan 2021 14:32:19 -0000	1.1.2.21
+++ openacs-4/packages/acs-tcl/tcl/00-icanuse-procs.tcl	14 Jan 2021 14:40:33 -0000	1.1.2.22
@@ -106,6 +106,10 @@
 ::acs::register_icanuse "ns_writer"                 {[info commands ::ns_writer] ne ""}
 ::acs::register_icanuse "nsv_dict"                  [acs::cmd_error_contains {nsv_dict get ""} -varname]
 
+# Note: NaviServer has ns_http since version 4.99.5, but supports the
+# run subcommand only since 4.99.15.
+::acs::register_icanuse "ns_http" [acs::cmd_has_subcommand ns_http run]
+
 #
 # Add some compatibility procs for AOLserver or older NaviServer versions
 #
Index: openacs-4/packages/acs-tcl/tcl/http-client-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/http-client-procs.tcl,v
diff -u -r1.30.2.16 -r1.30.2.17
--- openacs-4/packages/acs-tcl/tcl/http-client-procs.tcl	13 Jan 2021 13:16:46 -0000	1.30.2.16
+++ openacs-4/packages/acs-tcl/tcl/http-client-procs.tcl	14 Jan 2021 14:40:33 -0000	1.30.2.17
@@ -209,15 +209,7 @@
 
     set preferred [lindex $preference 0]
 
-    if {$preferred eq "native" &&
-        [ns_info name] eq "NaviServer" &&
-        [apm_version_names_compare \
-            [regsub -nocase {rc[[:digit:]]*$} [ns_info patchlevel] {}] \
-            "4.99.15"] >= 0
-    } {
-        # Naviserver has ns_http since before version 4.99.15, but
-        # with different features and syntax that we do not want to
-        # support anymore. Fallback will be curl in these cases.
+    if {$preferred eq "native" && [acs::icanuse ns_http]} {
         return "native"
     } elseif {[util::which curl] ne ""} {
         return "curl"