diff --git a/angrop/chain_builder/mem_writer.py b/angrop/chain_builder/mem_writer.py
index 52cdee9..349e036 100644
--- a/angrop/chain_builder/mem_writer.py
+++ b/angrop/chain_builder/mem_writer.py
@@ -220,7 +220,7 @@ def _write_to_mem_with_gadget(self, gadget, addr_val, data, use_partial_controll
 
         # constrain the addr
         test_state.add_constraints(the_action.addr.ast == addr_bvs, addr_bvs == addr_val.data)
-        pre_gadget_state.add_constraints(the_action.addr.ast == addr_bvs, addr_bvs = addr_val.data)
+        pre_gadget_state.add_constraints(the_action.addr.ast == addr_bvs, addr_bvs == addr_val.data)
         pre_gadget_state.options.discard(angr.options.AVOID_MULTIVALUED_WRITES)
         state = rop_utils.step_to_unconstrained_successor(self.project, pre_gadget_state)