diff --git a/libsolutil/LP.cpp b/libsolutil/LP.cpp
index 9df17f47f..f964b029b 100644
--- a/libsolutil/LP.cpp
+++ b/libsolutil/LP.cpp
@@ -353,7 +353,7 @@ void eraseIndices(T& _data, vector<bool> const& _indices)
 	T result;
 	for (size_t i = 0; i < _data.size(); i++)
 		if (!_indices[i])
-			result.emplace_back(move(_data[i]));
+			result.push_back(move(_data[i]));
 	_data = move(result);
 }
 
diff --git a/libsolutil/LinearExpression.h b/libsolutil/LinearExpression.h
index 0d038d260..d2ed920ed 100644
--- a/libsolutil/LinearExpression.h
+++ b/libsolutil/LinearExpression.h
@@ -39,6 +39,7 @@ using rational = boost::rational<bigint>;
 /**
  * A linear expression of the form
  * factors[0] + factors[1] * X1 + factors[2] * X2 + ...
+ * where the variables X_i are implicit.
  */
 struct LinearExpression
 {
@@ -72,7 +73,9 @@ struct LinearExpression
 	auto begin() const { return factors.begin(); }
 	auto end() const { return factors.end(); }
 
-	void emplace_back(rational _value) { factors.emplace_back(move(_value)); }
+	void push_back(rational _value) { factors.push_back(move(_value)); }
+
+	size_t size() const { return factors.size(); }
 
 	void resize(size_t _size)
 	{
@@ -88,15 +91,13 @@ struct LinearExpression
 
 	bool isConstant() const
 	{
-		return ranges::all_of(factors | ranges::views::tail, [](rational const& _v) { return _v.numerator() == 0; });
+		return ranges::all_of(factors | ranges::views::tail, [](rational const& _v) { return !_v; });
 	}
 
-	size_t size() const { return factors.size(); }
-
 	LinearExpression& operator/=(rational const& _divisor)
 	{
 		for (rational& x: factors)
-			if (x.numerator())
+			if (x)
 				x /= _divisor;
 		return *this;
 	}
@@ -104,7 +105,7 @@ struct LinearExpression
 	LinearExpression& operator*=(rational const& _factor)
 	{
 		for (rational& x: factors)
-			if (x.numerator())
+			if (x)
 				x *= _factor;
 		return *this;
 	}
@@ -112,7 +113,7 @@ struct LinearExpression
 	friend LinearExpression operator*(rational const& _factor, LinearExpression _expr)
 	{
 		for (rational& x: _expr.factors)
-			if (x.numerator())
+			if (x)
 				x *= _factor;
 		return _expr;
 	}
@@ -120,10 +121,10 @@ struct LinearExpression
 	LinearExpression& operator-=(LinearExpression const& _y)
 	{
 		if (size() < _y.size())
-			factors.resize(_y.size());
+			resize(_y.size());
 		for (size_t i = 0; i < size(); ++i)
-			if (_y.factors[i].numerator())
-				factors[i] -= _y.factors[i];
+			if (i < _y.size() && _y[i])
+				(*this)[i] -= _y[i];
 		return *this;
 	}
 
@@ -137,10 +138,10 @@ struct LinearExpression
 	LinearExpression& operator+=(LinearExpression const& _y)
 	{
 		if (size() < _y.size())
-			factors.resize(_y.size());
+			resize(_y.size());
 		for (size_t i = 0; i < size(); ++i)
-			if (_y.factors[i].numerator())
-				factors[i] += _y.factors[i];
+			if (i < _y.size() && _y[i])
+				(*this)[i] += _y[i];
 		return *this;
 	}