diff --git a/backends/aiger/xaiger.cc b/backends/aiger/xaiger.cc
index 6ca24bd7e..e060efece 100644
--- a/backends/aiger/xaiger.cc
+++ b/backends/aiger/xaiger.cc
@@ -471,7 +471,7 @@ struct XAigerWriter
 							SigBit O = sigmap(b);
 							if (O != b)
 								alias_map[O] = b;
-							input_bits.erase(b);
+							input_bits.erase(O);
 							undriven_bits.erase(O);
 						}
 					}