diff --git a/3rdparty/rbdl/include/rbdl/SimpleMath/SimpleMath.h b/3rdparty/rbdl/include/rbdl/SimpleMath/SimpleMath.h
index c99386d..2e867e1 100644
--- a/3rdparty/rbdl/include/rbdl/SimpleMath/SimpleMath.h
+++ b/3rdparty/rbdl/include/rbdl/SimpleMath/SimpleMath.h
@@ -1555,7 +1555,6 @@ private:
     typedef Matrix<value_type, Derived::RowsAtCompileTime, 1> ColumnVector;
 
     bool mIsFactorized;
-    Matrix<value_type, Derived::RowsAtCompileTime, Derived::ColsAtCompileTime> mQ;
     Derived mL;
 
 public:
@@ -1624,13 +1623,13 @@ public:
     Derived inverse() const {
         assert (mIsFactorized);
 
-        VectorXd rhs_temp = VectorXd::Zero(mQ.cols());
-        MatrixXXd result (mQ.cols(), mQ.cols());
+        VectorXd rhs_temp = VectorXd::Zero(mL.cols());
+        MatrixXXd result (mL.cols(), mL.cols());
 
-        for (unsigned int i = 0; i < mQ.cols(); i++) {
+        for (unsigned int i = 0; i < mL.cols(); i++) {
             rhs_temp[i] = 1.;
 
-            result.block(0, i, mQ.cols(), 1) = solve(rhs_temp);
+            result.block(0, i, mL.cols(), 1) = solve(rhs_temp);
 
             rhs_temp[i] = 0.;
         }