diff --git a/kernel/rtlil.cc b/kernel/rtlil.cc
index 9bb218f221b..a3801116e13 100644
--- a/kernel/rtlil.cc
+++ b/kernel/rtlil.cc
@@ -200,13 +200,15 @@ const pool<IdString> &RTLIL::builtin_ff_cell_types() {
 	return res;
 }
 
+#define check(condition) log_assert(condition && "malformed Const union")
+
 Const::bitvectype& Const::get_bits() const {
-	log_assert(is_bits() && "malformed Const union");
+	check(is_bits());
 	return *get_if_bits();
 }
 
 std::string& Const::get_str() const {
-	log_assert(is_str() && "malformed Const union");
+	check(is_str());
 	return *get_if_str();
 }
 
@@ -260,7 +262,7 @@ RTLIL::Const::Const(const RTLIL::Const &other) {
 	else if (is_bits())
 		new ((void*)&bits_) bitvectype(other.get_bits());
 	else
-		log_assert(false && "malformed Const union");
+		check(false);
 }
 
 RTLIL::Const::Const(RTLIL::Const &&other) {
@@ -271,7 +273,7 @@ RTLIL::Const::Const(RTLIL::Const &&other) {
 	else if (is_bits())
 		new ((void*)&bits_) bitvectype(std::move(other.get_bits()));
 	else
-		log_assert(false && "malformed Const union");
+		check(false);
 }
 
 RTLIL::Const &RTLIL::Const::operator =(const RTLIL::Const &other) {
@@ -279,7 +281,7 @@ RTLIL::Const &RTLIL::Const::operator =(const RTLIL::Const &other) {
 	if (other.is_str()) {
 		if (!is_str()) {
 			// sketchy zone
-			log_assert(is_bits() && "malformed Const union");
+			check(is_bits());
 			bits_.~bitvectype();
 			(void)new ((void*)&str_) std::string();
 		}
@@ -288,14 +290,14 @@ RTLIL::Const &RTLIL::Const::operator =(const RTLIL::Const &other) {
 	} else if (other.is_bits()) {
 		if (!is_bits()) {
 			// sketchy zone
-			log_assert(is_str() && "malformed Const union");
+			check(is_str());
 			str_.~string();
 			(void)new ((void*)&bits_) bitvectype();
 		}
 		tag = other.tag;
 		get_bits() = other.get_bits();
 	} else {
-		log_assert(false && "malformed Const union");
+		check(false);
 	}
 	return *this;
 }
@@ -306,7 +308,7 @@ RTLIL::Const::~Const() {
 	else if (is_str())
 		str_.~string();
 	else
-		log_assert(false && "malformed Const union");
+		check(false);
 }
 
 bool RTLIL::Const::operator<(const RTLIL::Const &other) const
@@ -450,7 +452,7 @@ int RTLIL::Const::size() const {
 	if (is_str())
 		return 8 * str_.size();
 	else {
-		log_assert(is_bits() && "malformed Const union");
+		check(is_bits());
 		return bits_.size();
 	}
 }
@@ -459,7 +461,7 @@ bool RTLIL::Const::empty() const {
 	if (is_str())
 		return str_.empty();
 	else {
-		log_assert(is_bits() && "malformed Const union");
+		check(is_bits());
 		return bits_.empty();
 	}
 }
@@ -468,7 +470,7 @@ void RTLIL::Const::bitvectorize() const {
 	if (tag == backing_tag::bits)
 		return;
 
-	log_assert(is_str() && "malformed Const union");
+	check(is_str());
 
 	bitvectype new_bits;
 
@@ -596,6 +598,7 @@ RTLIL::Const RTLIL::Const::extract(int offset, int len, RTLIL::State padding) co
 		ret_bv.push_back(i < GetSize(*this) ? (*this)[i] : padding);
 	return RTLIL::Const(ret_bv);
 }
+#undef check /* check(condition) for Const */
 
 bool RTLIL::AttrObject::has_attribute(const RTLIL::IdString &id) const
 {