diff --git a/passes/opt/opt_clean.cc b/passes/opt/opt_clean.cc
index e6d1b2f64..f1d21435c 100644
--- a/passes/opt/opt_clean.cc
+++ b/passes/opt/opt_clean.cc
@@ -271,6 +271,9 @@ bool compare_signals(RTLIL::SigBit &s1, RTLIL::SigBit &s2, SigPool &regs, SigPoo
 			return conns.check_any(s2);
 	}
 
+	if (w1 == w2)
+		return s2.offset < s1.offset;
+
 	if (w1->port_output != w2->port_output)
 		return w2->port_output;
 
@@ -343,7 +346,7 @@ bool rmunused_module_signals(RTLIL::Module *module, bool purge_mode, bool verbos
 		RTLIL::Wire *wire = it.second;
 		for (int i = 0; i < wire->width; i++) {
 			RTLIL::SigBit s1 = RTLIL::SigBit(wire, i), s2 = assign_map(s1);
-			if (!compare_signals(s1, s2, register_signals, connected_signals, direct_wires))
+			if (compare_signals(s2, s1, register_signals, connected_signals, direct_wires))
 				assign_map.add(s1);
 		}
 	}