1 files changed, 2 insertions, 0 deletions
diff --git a/passes/sat/sat.cc b/passes/sat/sat.cc
index dd56d8c71..bcc690fa3 100644
--- a/passes/sat/sat.cc
+++ b/passes/sat/sat.cc
@@ -268,6 +268,8 @@ struct SatHelper
 				RTLIL::SigSpec removed_bits;
 				for (int i = 0; i < lhs.size(); i++) {
 					RTLIL::SigSpec bit = lhs.extract(i, 1);
+					if (bit.is_fully_const() && rhs[i] == State::Sx)
+						rhs[i] = bit;
 					if (!satgen.initial_state.check_all(bit)) {
 						removed_bits.append(bit);
 						lhs.remove(i, 1);