diff --git a/lslopt/lslfuncopt.py b/lslopt/lslfuncopt.py
index 809444d..91dc16c 100644
--- a/lslopt/lslfuncopt.py
+++ b/lslopt/lslfuncopt.py
@@ -305,7 +305,7 @@ def OptimizeFunc(self, parent, index):
                 newnode = nr(nt='+', t='string', SEF=True,
                     ch=[CastDL2S(self, child[0], i),
                         nr(nt='+', t='string', SEF=True,
-                           ch=[self.Cast(child[1], 'string'), newnode]
+                           ch=[self.Cast(child[1], 'string').copy(), newnode]
                         )
                     ])
             parent[index] = newnode
diff --git a/unit_tests/regression.suite/issue-23.lsl b/unit_tests/regression.suite/issue-23.lsl
new file mode 100644
index 0000000..8195bed
--- /dev/null
+++ b/unit_tests/regression.suite/issue-23.lsl
@@ -0,0 +1,11 @@
+default
+{
+    state_entry()
+    {
+        string tmp0 = llGetScriptName();
+        list tmp1 = [llGetOwner(), llGetOwner()];
+        list tmp2 = [llGetScriptName(), llGetScriptName()];
+        string encoded = llDumpList2String([tmp0, llList2CSV(tmp1), "Hello", 123, llList2CSV(tmp2)], "|");
+        llOwnerSay(encoded);
+    }
+}
diff --git a/unit_tests/regression.suite/issue-23.out b/unit_tests/regression.suite/issue-23.out
new file mode 100644
index 0000000..8c27c48
--- /dev/null
+++ b/unit_tests/regression.suite/issue-23.out
@@ -0,0 +1,11 @@
+default
+{
+    state_entry()
+    {
+        string tmp0 = llGetScriptName();
+        list tmp1 = (list)llGetOwner() + llGetOwner();
+        list tmp2 = (list)llGetScriptName() + llGetScriptName();
+        string encoded = tmp0 + ("|" + (llList2CSV(tmp1) + ("|Hello|123|" + llList2CSV(tmp2))));
+        llOwnerSay(encoded);
+    }
+}
diff --git a/unit_tests/regression.suite/issue-23.run b/unit_tests/regression.suite/issue-23.run
new file mode 100644
index 0000000..e76e2cd
--- /dev/null
+++ b/unit_tests/regression.suite/issue-23.run
@@ -0,0 +1 @@
+./main.py -O addstrings -