diff --git a/src/interp/compile.zig b/src/interp/compile.zig
index 3e99f98..bdde346 100644
--- a/src/interp/compile.zig
+++ b/src/interp/compile.zig
@@ -94,7 +94,9 @@ const sz_code_tmp = struct {
             },
             .seq => |s| {
                 try self.append(src, s.a);
+                try self.clean_stack(s.a);
                 try self.append(src, s.b);
+                try self.clean_stack(s.b);
             },
             .unop => |u| {
                 try self.append(src, u.expr);
@@ -103,7 +105,13 @@ const sz_code_tmp = struct {
             .assign => |a| {
                 try self.append(src, a.rhs);
                 try self.append_assign(src, a.lhs);
-            }
+            },
+        }
+    }
+    fn clean_stack(self: *sz_code_tmp, expr: *const Expr) !void {
+        switch (expr.*) {
+            .atom, .binop, .unop => try self.bc.append(.{ .pop = {} }),
+            else => {},
         }
     }
     fn append_assign(self: *sz_code_tmp, src: []const u8, expr: *const Expr) !void {
@@ -131,6 +139,6 @@ pub fn compile(allocator: std.mem.Allocator, src: []const u8) !sz_code {
     const expr = try p.parse(src);
     var code = sz_code_tmp{ .consts = std.ArrayList(sz_obj).init(allocator), .vars = std.ArrayList(sz_obj).init(allocator), .bc = std.ArrayList(sz_inst).init(allocator), .name = std.StringHashMap(usize).init(allocator)};
     try code.append(src, expr);
-    try code.bc.append(.{ .pop = {} });
+    try code.clean_stack(expr);
     return code.finalize();
 }