diff --git a/kernel/rtlil.cc b/kernel/rtlil.cc
index cb0f7da78..d705813d9 100644
--- a/kernel/rtlil.cc
+++ b/kernel/rtlil.cc
@@ -540,6 +540,12 @@ void RTLIL::Const::bitvectorize() const {
 	}
 }
 
+void RTLIL::Const::append(const RTLIL::Const &other) {
+	bitvectorize();
+	bitvectype& bv = get_bits();
+	bv.insert(bv.end(), other.begin(), other.end());
+}
+
 RTLIL::State RTLIL::Const::const_iterator::operator*() const {
 	if (auto bv = parent.get_if_bits())
 		return (*bv)[idx];
diff --git a/kernel/rtlil.h b/kernel/rtlil.h
index f9cacd151..33742cb70 100644
--- a/kernel/rtlil.h
+++ b/kernel/rtlil.h
@@ -738,6 +738,8 @@ public:
 	bool empty() const;
 	void bitvectorize() const;
 
+	void append(const RTLIL::Const &other);
+
 	class const_iterator {
 	private:
 		const Const& parent;