diff --git a/core/vdbe/mod.rs b/core/vdbe/mod.rs
index df7f78016..1ba6d2d60 100644
--- a/core/vdbe/mod.rs
+++ b/core/vdbe/mod.rs
@@ -1435,8 +1435,9 @@ impl Program {
                                 state.registers[*dest] = result;
                             }
                             ScalarFunc::ConcatWs => {
-                                let start_reg = *start_reg;
-                                let result = exec_concat_ws(&state.registers[start_reg..]);
+                                let result = exec_concat_ws(
+                                    &state.registers[*start_reg..*start_reg + arg_count],
+                                );
                                 state.registers[*dest] = result;
                             }
                             ScalarFunc::IfNull => {}
diff --git a/testing/scalar-functions.test b/testing/scalar-functions.test
index 8ede9f78b..d73434ea1 100755
--- a/testing/scalar-functions.test
+++ b/testing/scalar-functions.test
@@ -3,38 +3,38 @@
 set testdir [file dirname $argv0]
 source $testdir/tester.tcl
 
-do_execsql_test concat-1 {
+do_execsql_test concat-chars {
   select concat('l', 'i');
 } {li}
 
-do_execsql_test concat-2 {
+do_execsql_test concat-char-and-number {
   select concat('l', 1);
 } {l1}
 
-do_execsql_test concat-3 {
+do_execsql_test concat-char-and-decimal {
   select concat('l', 1.5);
 } {l1.5}
 
-do_execsql_test concat-4 {
+do_execsql_test concat-char-null-char {
   select concat('l', null, 'i');
 } {li}
 
-do_execsql_test concat_ws-1 {
+do_execsql_test concat_ws-numbers {
   select concat_ws(',', 1, 2);
 } {1,2}
 
-do_execsql_test concat_ws-2 {
+do_execsql_test concat_ws-single-number {
   select concat_ws(',', 1);
 } {1}
 
-do_execsql_test concat_ws-3 {
-  select concat_ws(0, 1, 2);
-} {102}
-
-do_execsql_test concat_ws-4 {
+do_execsql_test concat_ws-null {
   select concat_ws(null, 1, 2);
 } {}
 
+do_execsql_test concat_ws-multiple {
+  select concat_ws(',', 1, 2), concat_ws(',', 3, 4)
+} {1,2|3,4}
+
 do_execsql_test char {
   select char(108, 105)
 } {li}