diff --git a/SLS_C/src/builtin.c b/SLS_C/src/builtin.c
index ddecdd4..0b08986 100644
--- a/SLS_C/src/builtin.c
+++ b/SLS_C/src/builtin.c
@@ -1182,8 +1182,17 @@ Boolean builtin_sqrt(InterpreterState *interpreter_state) {
 }
 
 Boolean builtin_swap(InterpreterState *interpreter_state) {
-    (void)interpreter_state;
-    return FALSE;
+    if (interpreter_state->stack == NULL) return FALSE;
+    if (interpreter_state->stack->next == NULL) return FALSE;
+
+    StackItem *a = interpreter_state->stack;
+    StackItem *b = a->next;
+
+    a->next = b->next;
+    b->next = a;
+    interpreter_state->stack = b;
+
+    return TRUE;
 }
 
 Boolean builtin_tan(InterpreterState *interpreter_state) {