diff --git a/tools/pnnx/src/pass_level3/eliminate_noop_math.cpp b/tools/pnnx/src/pass_level3/eliminate_noop_math.cpp
index 75bccda89..310fbda32 100644
--- a/tools/pnnx/src/pass_level3/eliminate_noop_math.cpp
+++ b/tools/pnnx/src/pass_level3/eliminate_noop_math.cpp
@@ -130,6 +130,12 @@ static bool operator_is_all_constant(const Operator* op, float vf, int vi)
     if (op->type == "prim::Constant")
         return constant_is_all_constant(op, vf, vi);
 
+    if (op->type == "torch.zeros" || op->type == "torch.zeros_like")
+        return (vf == 0.f && vi == 0);
+
+    if (op->type == "torch.ones" || op->type == "torch.ones_like")
+        return (vf == 1.f && vi == 1);
+
     return false;
 }
 
@@ -163,7 +169,7 @@ void eliminate_noop_math(Graph& graph)
                     need_eliminate = true;
                     identity_input_id = 0;
                 }
-                else if (operator_is_all_constant(op0, 0.f, 0) && operator_is_all_constant(op0, 1.f, 1))
+                else if (operator_is_all_constant(op0, 0.f, 0) && operator_is_all_constant(op2, 1.f, 1))
                 {
                     // x <= 0 + b * 1
                     need_eliminate = true;