Fixed bugs reported by the mycology test suite

1 files changed, 2 insertions, 3 deletions

diff --git a/src/stack.zig b/src/stack.zig
index 09edd2e..c1f8696 100644
--- a/src/stack.zig
+++ b/src/stack.zig
@@ -12,9 +12,8 @@ pub const Stack = struct {
         self.allocator.destroy(self);
     }
     pub fn duplicate(self: *Stack) !void {
-        if (self.data.items.len > 0) {
-            try self.push(self.data.items[self.data.items.len - 1]);
-        }
+        const v = self.pop();
+        try self.pushVector([2]i64{ v, v });
     }
     test "duplicate" {
         var s = try Stack.init(std.testing.allocator);