diff --git a/lib/Tools/circt-bmc/ExternalizeRegisters.cpp b/lib/Tools/circt-bmc/ExternalizeRegisters.cpp
index 659ef0dfbff8..08358b270898 100644
--- a/lib/Tools/circt-bmc/ExternalizeRegisters.cpp
+++ b/lib/Tools/circt-bmc/ExternalizeRegisters.cpp
@@ -96,22 +96,15 @@ void ExternalizeRegistersPass::runOnOperation() {
           }
           mlir::Attribute initState;
           if (auto initVal = regOp.getInitialValue()) {
-            // Find the seq.initial op where the initial value is defined and
-            // fetch the operation inside that defines the value
-            auto initialOp =
-                regOp.getInitialValue().getDefiningOp<seq::InitialOp>();
-            if (!initialOp) {
+            // Find the constant op that defines the reset value in an initial
+            // block (if it exists)
+            if (!initVal.getDefiningOp<seq::InitialOp>()) {
               regOp.emitError("registers with initial values not directly "
                               "defined by a seq.initial op not yet supported");
               return signalPassFailure();
             }
-            auto index = cast<OpResult>(initVal).getResultNumber();
-            auto initValDef =
-                initialOp->getRegion(0).front().getTerminator()->getOperand(
-                    index);
-            // If it's defined by a constant op then just fetch the constant
-            // value - otherwise unsupported
-            if (auto constantOp = initValDef.getDefiningOp<hw::ConstantOp>()) {
+            if (auto constantOp = circt::seq::unwrapImmutableValue(initVal)
+                                      .getDefiningOp<hw::ConstantOp>()) {
               // Fetch value from constant op - leave removing the dead op to
               // DCE
               initState = constantOp.getValueAttr();