Index: openacs-4/packages/acs-tcl/tcl/utilities-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/utilities-procs.tcl,v
diff -u -N -r1.189.2.154 -r1.189.2.155
--- openacs-4/packages/acs-tcl/tcl/utilities-procs.tcl	7 Nov 2022 13:34:34 -0000	1.189.2.154
+++ openacs-4/packages/acs-tcl/tcl/utilities-procs.tcl	8 Nov 2022 09:55:39 -0000	1.189.2.155
@@ -2477,13 +2477,16 @@
             # way confusion through replacement of deleted content
             # with new stuff is avoided.
 
+            set str_length [string length "${str}${replace_with}"]
             set number 2
 
             foreach name $existing_names {
 
-                if { [regexp "${str}${replace_with}(\\d+)\$" $name match n] } {
-                    # matches the foo-123 pattern
-                    if { $n >= $number } { set number [expr {$n + 1}] }
+                if {[string range $name 0 $str_length-1] eq "${str}${replace_with}"} {
+                    set n [string range $name $str_length end]
+                    if {[string is integer -strict $n] && $n >= $number} {
+                        set number [incr n]
+                    }
                 }
             }
 
Index: openacs-4/packages/acs-tcl/tcl/test/utilities-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/test/Attic/utilities-procs.tcl,v
diff -u -N -r1.1.2.12 -r1.1.2.13
--- openacs-4/packages/acs-tcl/tcl/test/utilities-procs.tcl	11 Oct 2022 09:04:58 -0000	1.1.2.12
+++ openacs-4/packages/acs-tcl/tcl/test/utilities-procs.tcl	8 Nov 2022 09:55:40 -0000	1.1.2.13
@@ -82,6 +82,10 @@
                           -existing_names {a_ßcoooetcpasswdl#_f__ilename_.extension} \
                           $str]
         aa_equals "Sanitizing to an existing filename with resolving is fine" $resolved [string tolower "A_ßCoOOetcpasswdl#_f__ilename_.extension"]_2
+
+        aa_false "Sanitizing with not balanced parantheses in the filename does not throw an error" [catch {
+            aa_equals "Sanitizing to an existing filename with resolving is fine" [ad_sanitize_filename -existing_names {foo( foo(-3} "foo("] "foo(-4"
+        }]
     }